High density composite material

ABSTRACT

The present invention is related to a family of materials that may act as a replacement for lead in applications where the high density of lead is important, but where the toxicity of lead is undesirable. The present invention more particularly provides a high density material comprising tungsten, fiber and binder. Methods and compositions of such materials and applications thereof are disclosed herein.

This application is a divisional application of U.S. application Ser.No. 08/884,001, filed Jun. 27, 1997 now U.S. Pat. No. 6,048,379 andclaims priority to provisional application No. 60/020,914 filed Jun. 28,1996.

The government may own certain rights in the present invention pursuantto United States Army contract number DAAE 30-95-C-0021.

BACKGROUND OF THE INVENTION

The present application is a continuation-in-part of co-pendingProvisional U.S. patent application Ser. No. 60/020,914 filed Jun. 28,1996. The entire text of the above-referenced disclosure is specificallyincorporated by reference herein without disclaimer.

1. Field of the Invention

The present invention relates generally to the fields of polymers andhigh density compositions. More particularly, it concerns materials thatmay act as a replacement for lead in applications requiring lead's highdensity, but where the toxic effects of lead are undesirable. Further,the high density composites of the present invention may be employed inany application where a high density material is required.

2. Description of Related Art

Each year, approximately 689 million rounds of small arms ammunition(.22 caliber through .50 caliber) are fired during training by the Army,Navy, Air Force, Marine Corps, National Guard, and Reserves in theUnited States. An additional 10 million rounds are fired annually by theDepartment of Energy. The ammunition projectiles used for this trainingconsist of lead antimony cores, or cores, encased in a copper alloyjacket. Use of these projectiles results in approximately 2,000 tons oflead per year being introduced into the environment. Lead contaminationof soil, sediments, surface and groundwater have been confirmed throughinvestigations conducted at Army, Navy, Air Force, Marine Corps, CoastGuard and private small arms ranges throughout the United States andEurope. Lead uptake in vegetation at a Marine Corps small arms range inQuantico, Virginia showed lead levels as high as 23,200 parts permillion. Remediation of contaminated ranges has proven to be extremelyexpensive and provides only a temporary solution. The Navy reportshazardous waste removal from one small arms firing berm cost $2.5million with an additional $100,000 per year required for leadcontamination monitoring. Sixteen Navy small arms firing ranges are nowrequired to improve hazardous waste maintenance at a predicted cost of$37.2 million. In addition, the September 1995 “Cost Analysis forMunitions Rule” prepared by the U.S. Army Concepts Analysis Agencyindicate the cost to remediate an outdoor small arms range isapproximately $150,000 per acre. Currently there are 120 ranges closingor scheduled to be closed as a result of Base Realignment and Closurerecommendations which account for an estimated 4,185 acres or a total of$627 million.

In order for firing ranges to remain open, expensive cleanup proceduresmust be employed that provide only a temporary solution to the problem.A non-toxic, lead-free, environmentally safe, cost effective replacementprojectile core material is required to enable firing ranges to remainopen and to eliminate costly cleanup procedures. The density of theprojectile should be close to that of a lead projectile for realisticperformance simulation. Materials of a lower density decrease projectilerange and penetration.

In addition, there is mounting concern over the use of lead shot forbird hunting, due to ingestion of the shot by birds and other animals aswell as contamination of wetland areas. Indeed there has beenlegislation in the United States and other countries which bans the useof lead shots in waterfowl shots. Moreover, such a lead substitute orhigh density material will find many other applications, such as forweights, acoustic dampening or vibration dampening, and in radiationshielding applications, including protective clothing, medical clothingand clothing for use in nuclear reactors.

SUMMARY OF THE INVENTION

The present invention, in a general and overall sense, concerns a familyof materials that may act as a replacement for lead in applicationswhere the high density of lead is important, but where the toxicity oflead is undesirable. Thus there is presented in a particular aspect ahigh density composite for use in applications in which lead or anyother high density material may be required.

Thus in a particular embodiment, there is provided a high densitycomposition of matter, comprising tungsten powder, a fiber and a bindermaterial. In particular embodiments, the tungsten comprises betweenabout 5% and about 95% of the composite. In other embodiments, thetungsten comprises between about 10% and about 80% of the composite. Inother embodiments, the tungsten comprises between about 15% and about70% of the composite. In alternate embodiments, the tungsten comprisesbetween about 25% and about 50% of the composite. In other embodiments,the tungsten comprises between about 35% and about 40% of the composite.Of course these are exemplary percentages and the tungsten may compriseany percentage between these figures, for example, about 5%, 6%, 7%, 8%,9%, 12%, 14%, 16%, 20%, 21%, 22%, 23%, 24%, 26%, 28%, 30%, 32%, 34%,36%, 38%, 42%, 44%, 46%, 48% 52%, 54%, 56%, 58%, 60%, 62%, 64%, 66%,68%, 72%, 74%, 76%, 78%, 82%, 84%, 86%, or 88% of the composite weight.

In other aspects of the present invention the tungsten powder particlesize is between about 2 and about 40 microns in diameter. In analternative embodiment the tungsten powder particle size is betweenabout 4 and about 8 microns in diameter. In yet another embodiment, thetungsten powder particle size is between about 20 and about 40 micronsdiameter. Of course these are exemplary measurements and the powder maycomprise a particle size of about 4, 5, 6, 7, 9, 10, 11, 12, 14, 16, 18,21, 22, 23, 24, 25, 28, 30, 31, 32, 33, 34, 35, 36, 37, 38 or 39 micronsin diameter. In certain embodiments, it may be desirable to havetungsten powder comprised of particles having varying sizes of diameter.In other embodiments, the powder may be comprised of particles ofuniform size of diameter.

In a particular embodiment of the present invention, the fiber maycomprise stainless steel, copper, aluminum, nylon, Kevlar®, Spectra®,nickel, glass or carbon. In more particular aspects, the fiber isstainless steel fiber. In preferred embodiments, the fiber comprisesbetween about 3% and about 30% of the composite weight. In other aspectsthe fiber comprises between about 10% and about 20% of the compositeweight.

In alternate embodiments, the fiber comprises between about 15% andabout 18% of the composite weight. Of course these are exemplarypercentages and the fiber may comprise any percentage between thesefigures, for example, about 4%, 5%, 6%, 7%, 8%, 9%,10%, 12%, 14%, 16%,19%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, or 29% of the compositeweight.

In yet another aspect of the present invention the binder is a polymericbinder. In particular aspects the polymeric binder may be selected fromthe group consisting of cellulose, fluoro-polymer, ethyleneinter-polymer alloy elastomer, ethylene vinyl acetate, ionomer, nylon,polythermide, polyester elastomer, polyester sulfone, polyphenyl amide,polypropylene, polyvinylidene fluoride or thermoset polyurea elastomer.

In more particular embodiments, the polymeric binder is Nylon 12® andpolyester elastomer. In more specific embodiments the polymeric bindercomprises between about 1% to about 30% weight ratio of the composite.In other embodiments, the polymeric binder is at a concentration ofabout 2% to about 20% weight ratio. In still further embodiments, thepolymeric binder comprises between about 5% to about 15% weight ratio ofthe composite. In other embodiments, the polymeric binder comprisesbetween about 8% to about 12% weight ratio of the composite.

The present invention further provides a high density plasticcomposition comprising a mixture of a base metal powder, fiber andbinder. In particular embodiments, the base metal powder may be osmium,iridium, platinum, rhenium, tungsten, gold, tantalum, rhodium,palladium, thallium, silver, molybdenum, bismuth, copper, cobalt,nickel, cadmium, niobium and iron. In particular embodiments the highdensity composition may be utilized as a radiation shielding material.In other embodiments, the radiation shielding material is a flexibleshielding material. In further embodiments, the composition may beutilized as modeling weights, fishing weights, flywheels, orprojectiles.

Other objects, features and advantages of the present invention willbecome apparent from the following detailed description. It should beunderstood, however, that the detailed description and the specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings form part of the present specification and areincluded to further demonstrate certain aspects of the presentinvention. The invention may be better is understood by reference to oneor more of these drawings in combination with the detailed descriptionof specific embodiments presented herein.

FIG. 1 shows a picture of compression molded tungsten powder/polymericbinder flexural test bars.

FIG. 2 shows a picture of the three point bend flexural test fixture anda flexural test bar installed in an Instron testing machine. A-supportpins; B-center pin with cylindrical tap; C-flexural test bar; D-supportbase.

FIG. 3 shows the maximum flexural load (lb) for various polymericbinders.

FIG. 4 shows the flexural strength (psi) for various polymeric binders.

FIG. 5 shows the maximum flexural displacement (in.) for variouspolymeric binders.

FIG. 6 shows the flexural modulus (psi) for various polymeric binders.

FIG. 7 shows a fractured tensile test bar after being pulled in theInstron tensile testing machine.

FIG. 8 compares the tensile strengths of Nylon 12®/Stainless Steel fibercomposite, Nylon 12® composite, polyester elastomer composite and lead.

FIG. 9 shows the elongation at break of Nylon 12®/Stainless Steel fibercomposite, Nylon 12® composite, polyester elastomer composite and lead.

FIG. 10 shows the tensile modulus (ksi) of Nylon 12®/Stainless Steelfiber composite, Nylon 12® composite, polyester elastomer composite andlead.

FIG. 11 shows a test specimen four cavity model injection mold. A-ASTMD638 Type 1 tensile bar; B-impact disc; C-impact bar; D-ASTM D638 Type Vtensile bar.

FIG. 12 shows a picture of the injection molded composite materialtensile test bars. A-broken tensile test bar after tensile test;

FIG. 13 shows a picture of a tungsten powder polymer binder injectionmolded projectile core (C), a lead projectile core (B), and a copperjacketed lead projectile core (A).

FIG. 14 shows a vertical drop compressive impact test that provides aqualitative assessment of the impact performance of the TPP compositematerial projectile cores and lead projectile cores.

FIG. 15 shows vertical drop (6 inch drop height) impact test results forNylon 12® tungsten powder composite projectile core and lead forcomparison.

FIG. 16 shows vertical drop (12 inch drop height) impact test resultsfor Nylon 12® tungsten powder composite projectile core and lead forcomparison.

FIG. 17 shows vertical drop (18 inch drop height) impact test resultsfor Nylon 12® tungsten powder composite projectile core and lead forcomparison.

FIG. 18 shows vertical drop (6 inch drop height) impact test results forNylon 12® tungsten powder with stainless steel fiber compositeprojectile core.

FIG. 19 shows vertical drop (12 inch drop height) impact test resultsfor Nylon 12® tungsten powder with stainless steel fiber compositeprojectile core.

FIG. 20 shows vertical drop (18 inch drop height) impact test resultsfor Nylon 12® tungsten powder with stainless steel fiber compositeprojectile core.

FIG. 21 shows vertical drop (6 inch drop height) impact test results forpolyester elastomer (TEXIN 480A) tungsten powder with stainless steelfiber composite projectile core.

FIG. 22 shows vertical drop (12 inch drop height) impact test resultsfor polyester elastomer (TEXIN 480A) tungsten powder with stainlesssteel fiber composite projectile core.

FIG. 23 shows vertical drop (18 inch drop height) impact test resultsfor polyester elastomer (TEXIN 480A) tungsten powder with stainlesssteel fiber composite projectile core.

FIG. 24 shows non-toxic lead-free fishing weight prototypes and theirlead counterparts.

FIG. 25 shows model train weights. A commercially available lead modeltrain add-on weight is shown on the left and a lead-free prototypecompression molded by of the present invention is shown in the center,Lead-free bar-stock is shown on the right. The lead-free train weightsare made of tungsten powder and have a density of 11.0 g/cc.

FIG. 26 shows a design drawing of a 7.62 mm projectile core (slug).

FIG. 27 shows a design drawing of a 7.62 mm bullet.

FIG. 28 shows a design drawing of a 7.62 mm M80 Nato Ball Cartridge.

FIG. 29 shows a design drawing of prototype 7.62 mm projectile coresingle cavity injection mold.

FIG. 30A, FIG. 30B and FIG. 30C show inspection results depicting slugweight (FIG. 30A), slug length (FIG. 30B) and slug diameter (FIG. 30C)for tungsten/Nylon 12® and tungsten/Nylon 12®/stainless steelcomposites.

FIG. 31 shows an illustration of penetration depth, length and height ofthe temporary cavity made by firing of projectiles of the presentinvention into ballistic gelatin.

FIG. 32 Set up for toxic fume test (top view).

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Lead from spent lead bullets represents a major source of environmentalpollution as well as posing a potential health risk to both shooters andrange personnel alike. Lead bullet residue left in the earthen berms ofoutdoor ranges can leach into the soil and contaminate water tables.Indoor ranges require extensive and expensive air filtration systems tooperate safely as lead is introduced into the atmosphere as theprojectile exits the barrel. Improved bullet traps are also required topermit lead collection and recycling. Outdoor ranges require constantsoil remediation.

The present invention provides compositions that may be used as leadsubstitutes, having a density similar to or greater than lead and beingsubstantially less toxic to the user. The compositions of the presentinvention thus provide a new, relatively non-toxic, high performancereplacement for metallic lead that can play a part in the ongoingtransition from environmentally hazardous materials to ecologicallyacceptable ones. The compositions of the present will be useful not onlyin the manufacture of ammunitions but also in any applications requiringthe use of a high density material. For example, the materials areuseful as weights, such as counterweights, fishing weights, wheelweights, flywheels or for use in model applications, such as in modelrailroading. Other similar applications include use as an acousticdampening or vibration dampening material. Also, the high densitymaterial will find use in radiation shielding applications, for example,in radiotherapy and routine X-ray examinations and those applicationsrequiring a radiation shielding compound that may be placed in smallspaces, such as cracks. As defined herein “high density” refers to adensity that is near to or higher than the density of lead.

As stated earlier, the compositions of the present invention may be usedin the manufacture of practice ammunition for all types of rifles andpistols. If the lead-free projectiles are also frangible, they haveapplications when ricochet poses a danger to innocent parties.Applications for frangible non-toxic projectiles includes indoor/outdoorfiring ranges; police and military training and qualification;commercial institutions; industrial installations; banks; prisons/jails;nuclear power plants; chemical processing plants; hospitals; anduniversities.

The non-toxic projectile core technology of the present invention may beused to replace lead shotgun pellets, now prohibited for use inwaterfowl hunting. The tungsten-based pellets will have similarperformance to lead shot, unlike steel shot that is currently being usedas a replacement for lead shot. Bismuth is also used, but this materialis not as dense as lead, making it an undesirable material in lead shotreplacement. Rifled slugs for shotguns and air rifle pellets may also bemanufactured utilizing the non-toxic tungsten formulations according tothe present invention.

Further, the compounds may be formed into sheets or blocks useful inradiation shielding applications. Also it is contemplated that the highdensity materials of the present invention can be machined to formcomplex shields, housings or assemblies. Other radiation shieldingapplications include use in clothing worn by personnel exposed toradiation sources. Such dense, and non-toxic materials may further beformulated to be flexible and will find applications in protectiveclothing and other protective gear for medical and dental personnel,persons involved in the nuclear power or defense industries, and anyother application where such clothing or apparel is worn. Lead is asoft, toxic and structurally weak metal and is therefore unsuitable forcertain such applications.

The material may be injection or compression molded into a variety ofshapes. Injection molding fabrication using the material allows for highvolume, low cost fabrication. Products utilizing the high densitymaterials of the present invention may also be fabricated usingthermoset and thermoplastic extrusion, thermoset and thermoplasticpultrusion, compression, centrifugal molding, rotational molding, blowmolding, casting, calendering, liquid fill thermoset molding or filamentwinding to form a variety of shapes.

The material of the present formulations comprises a tungsten powder asa high density component. Tungsten powder is relatively non-toxic and issuitable for commercial applications. Because solid metallic tungsten isa very hard material and melts at an extremely high temperature (approx.3410° C., the highest melting point of all metals), the presentformulations allows injection and compression molding and otherpreviously mentioned methods, thus avoiding difficulties that may beencountered with working with pure tungsten.

A novel aspect of the present formulations is the use of fibers to forma composite material comprising tungsten powder, polymeric binders, andfibers. The fibers may be stainless steel, or other metallic fibers suchas copper, nickel, niobium, or titanium. Alternatively, non-metallicfibers, such as glass fibers, Kevlar®, Spectra®, graphite, carbon, orboron, may be used to increase the tensile strength of the composition.It is possible to enhance the physical properties of the composition byadding various fibers, either singly or in combination with each other.For example, use of fibers softer than steel, such as glass, cellulose,cotton, nickel or copper fibers, may result in reduction of barrel wearin projectile applications.

Another aspect of the invention is the use of thermoplastic andthermoset materials as a polymeric binder. Each type of binder may beused to vary the physical properties of the composite, for example fromvery hard to soft and flexible. As used herein, “TPP” means tungstenpowder/polymeric binder composite materials. In certain embodiments, thebinder may be a hot melt or thermosetting type of glue. In particularembodiments, the thermoset may comprise a single component whereas inother embodiments, the thermosets comprise a plurality of components.

The properties of the composition may be varied as well by the use oftungsten powders of different particle sizes. A composition may comprisea powder of a single particle size, or the composition may comprise atungsten powder blend with a distribution of different particle sizes.

In certain aspects, equal portions of a tungsten powder with sizedistributions of about 2-4 microns, about 4-8 microns, and about 20-40microns which are mixed with fibers and polymeric binder. Stainlesssteel fibers are added, for example, at about 5% by volume with thecomposition to improve tensile strength.

As previously mentioned, the compositions of the present invention maybe used as ionizing radiation shielding that is relatively non-toxic andeasy to apply. In this aspect, tungsten powder is mixed with the bulkcomponent of a two-part curing resin system, such as an epoxy resin. Theresultant mixture, having the viscosity of a caulking compound, iseasily stored until ready for use. Prior to application, a catalyst isadded and the mixture is thoroughly stirred. The material may then beapplied to any surface, for example into cracks, and allowed to cure.The resulting cured material could, for example, then serve as a patchfor radiation leaks in a radiation shielding system. In otherapplications, the composition may be used as radiation shielding inclinical applications, for example to form shields for use in radiationtherapy procedures. Alternatively it will be possible to employ thecompositions of the present invention in making aprons, gloves or otherapparel and shields for use in applications such as, for example, X-rayexaminations.

In other aspects, the formulations of the present invention are usefulin making a lead-free projectile, which comprises, for example, a powdermaterial that may be tungsten, tungsten carbide, ferrotungsten, and thelike. The formulation also comprises a fiber material that may be, forexample, stainless steel, copper, glass, zinc, and the like.Additionally, the formulation comprises a binder material that may be atwo-part curing resin, such as epoxy resin, polyurethane or polyesterresin, or other polymer material. One-component thermosets are oftencure initiated by air or moisture.

In certain other aspects of the invention, methods are provided formolding articles of the present invention into a variety of shapes,including projectiles, shot, radiation shielding blocks, customradiation shields with complex geometry, and the like. Also provided aremethods of preparing the formulations into a putty-like consistency thatmay be applied into cracks or holes to block radiation passage. Thecompositions of the present invention and methods for making and usingsuch compositions are described in further detail herein below.

Metal Powders

Table 1 presents a list of elemental metals that were considered aspotential candidates for use as lead substitutes in high densitycompositions. From the list of metals with a specific gravity greaterthan lead, it is evident that tungsten meets the physical requirementsof high density. Furthermore, tungsten has a low toxicity, making it anexcellent metal of choice in lead substitutes and other high densitymaterials.

TABLE 1 Potential Candidate Base Metals and Alloying Metals ElementalMetal Specific Gravity Potential Base Metals Osmium 22.48 Iridium 22.42Platinum 21.45 Rhenium 20.53 Tungsten 19.35 Gold 18.88 Tantalum 16.60Hafnium 13.31 Rhodium 12.40 Ruthenium 12.30 Palladium 12.02 Thallium11.85 Lead 11.43 Potential Alloying Metals Silver 10.50 Molybdenum 10.20Bismuth 9.80 Copper 8.92 Cobalt 8.90 Nickel 8.90 Cadmium 8.64 Niobium8.57 Iron 7.86

The great advantage of tungsten as a lead substitute material is that,in addition to being comparatively non-toxic, it has a very high density(19.25 g/cc). Commercially available tungsten powders can therefore bemixed and pressed with softer and lighter non-toxic metals, such as tinor zinc, to generate lead substitute materials with a range of densitiesas high as, or even higher than, that of lead.

Of course, it will be possible to produce a high density compositematerial in accordance with the present invention by using any of themetals shown in Table 1. Particularly preferred is tungsten, butbismuth, copper, cobalt, tantalum, nickel, silver and so forth can alsobe used.

In certain instances, copper was found to have a number of advantages asa useful material. It is relatively non-toxic and is widely accepted bythe shooting community through its extensive use as a jacketing metalfor lead projectiles. Solid copper has a reasonably high density of 8.96g/cc, which is about 80% of that of lead.

A survey of the periodic table of elements shows that metals withdensities higher than copper (such as silver, gold, tungsten, bismuth)are considerably more expensive than copper and have previously beenrejected as possible replacements for lead on grounds of affordability,however the methods and compositions of the present invention make thesematerials a useful and affordable alternative to lead and copper in someapplications. Finally, the high melting and boiling points of copperensure that very little of the copper metal will vaporize into an easilybreathable form (so called copper fume) either at the firing point or onbullet impact with indoor range steel baffling on bullet traps.

Copper in the metallic and powder form is not a severe pollutant. It iswidely used in military stores. Nearly all small arms cartridge casesare made from brass (an alloy of copper and zinc). Its excellentlubricating and flow characteristics also make it the metal of choicefor jacketing lead cores in small arms bullets. The price of copper isalso sufficiently high to ensure that brass cartridge cases are alwayseither reused or recovered for scrap. Expended copper bullet jacketsalso have value and can be recovered and recycled as scrap copper,further assisting reclamation of waste materials and protection of theenvironment. Copper alloys such as brass and bronze can also be used tomake bullets. These alloys are harder than copper and need to be pressedat higher pressures and sintered at lower temperatures.

Non-toxic metals such as zinc and tin are also potential candidates toreplace lead but, being less dense than copper and tungsten, may sufferfrom problems arising from lower projectile mass such as compatibilitywith commercially available propellants, reliable cycling and feeding ofweapons, realistic recoil energies and matching the trajectory of leadprojectiles. However, the present invention circumvents this problem byproviding methods of making composite materials that make the materialmore dense.

More volatile metals than copper, such as tin and zinc, are also proneto forming ingestible vapors at the high temperatures generated duringbullet impact on steel plates.

Metals such as gold, silver, platinum and palladium also have densitiesthat are close to or greater than the density of lead and wouldtherefore, be suitable as materials for the composites of the presentinvention. The drawback with these metals is that they are expensive;however, the present invention combines metals of a high density with,for example, Nylon 11® or Nylon 12® in order to make such compositesmore cost effective. Further other non-metallic components may be usedin combination with the disclosed compositions to form a material of therequisite density in a relatively cost effective manner. Suchnon-metallic components may include mineral ores for example, hematite.

In certain applications where projectiles are made, employing tungsten,or any of the other non-toxic metals listed herein as a component, it ispossible to demonstrate a uniform blending of the metal powders,essential to ensure consistent projectiles and other articles describedin the present invention. Furthermore, the composite projectiles matchstandard ball ammunition, both in weight and trajectory, over realistictraining distances. Lead substitutes using tungsten powder as acomponent are frangible but they tend to be much more penetratingagainst metal plates than other metal loaded polymer projectiles.

Metal Fibers

In order to reduce the cost and add strength to a tungstenpowder/polymeric binder composite material, the present inventors haveadded metal fibers at a low volume fraction. The inventors performed asurvey to identify suitable metal fibers for use in a projectile coreapplication. The metal fibers need to possess high strength, highspecific gravity and have a low cost. The survey revealed that the mostcost effective metal fibers with high strength and specific gravity arechopped stainless steel fibers. Stainless steel fibers are readilyavailable and are currently being added to injection moldable polymerresins at up to a 30% volume ratio for electromagnetic shieldingapplications. Fiber made from 316 stainless steel with a length of 0.125inches, a thickness of 75 microns, a specific gravity of 8.0 wasselected as a representative tungsten powder/polymeric binder materialadditive. In other embodiments, any of the metals listed in Table 1, mayfurther be formulated into fibers for use in the present invention.

Polymeric binders

Once tungsten was selected as the candidate metal powder, a survey wasperformed to identify potential polymeric binders for the tungstenpowder. As used herein a “binder” is a material that is used to providecohesion between the high density metal powder and the fibers such thatthe integrity of the metal and the fiber is maintained.

Table 2 presents a summary of selected properties for polymeric bindersconsidered for mixing with tungsten powder. The selection criteria usedto form this list of potential polymeric binder materials included goodductility (high elongation values), high strength, high modulus, highmelting temperatures, high impact strength, low water absorption and lowcost. The Nylon 6® and Nylon 6,6® resins were found to have high waterabsorption values. The polyethersulfone and polyphthalamide had lowelongation values. The cellulose resin was retained even though it alsohas low elongation because it is a biodegradable projectile corematerial. After consulting with U.S. Army ARDEC engineering personnel,it was determined that all of these candidate materials should bechemically compatible with the cartridge propellants. All of theselected candidate polymer resins are injection molding grades exceptfor the thermoset elastomer. The polyurea thermoset elastomer is a TexasResearch Institute/Austin MDI/Polamine 1000 formulation. The Polamine1000 polyurea elastomer formulation is prepared by mixing 38.02 g Dow2143L (a modified diphenylmethane diisocyanate) and 150 g Polamine 1000(an amine terminated polytetramethylene ether made by Air Products) withTeledyne C-8 tungsten powder for a final product density of 10.33 g/cc.This material is referred to hereinafter as “TRI/Austin MDI/Polamine1000 formulation”.

TABLE 2 Selected Properties of Candidate Binders Heat Notched WaterMelting Deflection Tensile Elongation Elongation Tensile Flexural IzodImpact Absorption at Polymeric Manufacturer Spec. Point Temp. atStrength At Yield At Break Modulus Modulus Strength 24 hr. binder(Grade) Grav. (F.) 263 psi (F.) (psi) (%) (%) (ksi) (ksi) (ft-lb/in)Immersion (%) Cellulose Planet 1.29 360 125 6,182 — 11 338 413 1.3 —Based Polymers (PT-C300ZT) ECTFE Ausimont 1.68 460 153 6,600 — 260 — 242N.B. 0.10 Fluoro- (Halar 5001LC) polymer Ethylene DuPont 1.20 365 —1,200 9 375 — — — — Inter- (ALCRYN polymer 2070NC) Alloy ElastomerEthylene- DuPont 0.95 415 — 2,600 — 800 — 3.7 — — Vinyl (ELVAX 360)Acetate Polymer Ionomer DuPont (Surlyn 0.95 480 — 5,600 — 305 — 79 N.B.— 8220) Nylon Hoechst 1.13 419 147 11,400  — 80 435 395 1.1 1.70 6 ®Celenase (2800) Nylon Hoechst 1.14 495 190 11,000  — 300 — 420 2.1 1.506,6 ® Celanese (1000) Nylon Atochem 1.04 367 115 10,000  — 390 — 170 —0.30 11 ® (BMFO) Nylon EMS-American 1.01 352 131 7,500 20  320 — 126 1.30.23 12 ® (Grilamide L20GHS) Poly- GE 1.27 675 392 15,200  7 60 — 4801.0 0.25 thermide (Ultem 1000) (PEI) Polyester Bayer 1.20 385 — 6,000 —500 1.7 4.5 — — Elastomer (Texin 480-A) Polyester- BASF 1.37 680 —13,000  — 6.7 380 — 13.0  0.30 sulfone (Ultrason (PES) E1010) Poly-AMOCO 1.15 590 248 11,000  6 30 350 380 18.0  0.68 phtal- (Amodel amideET-1001) (PPA) Poly- AMOCO 0.91 450 — 4,000 9 500 — 200 3.4 0.03propylene (ACCTUF 3434) Poly- Atisimont 1.77 315 185 7,500 — 250 200 2603.0 0.04 vinylidene (Hylar 461) Flouride (PVDF) Thermoset TRIAustin — —— 8,000 — 460 2.1 — — — Polyurea (MDI/Polamine Elastomer 1000)

Methods of making projectiles, shielding devices and other applicationsdescribed herein are well known to those of skill in the art. Theskilled artisan is referred to U.S. Pat. No. 5,264,022; 5,399,187;5,189,252; 4,949,645, and WO 9316349 for details on the use of alloys inthe preparation of projectiles, each of the aforementioned publicationsis incorporated herein by reference. U.S. Pat. No. 5,081,786 and WOpublication No. 9208346 (both incorporated herein by reference) describemethods of constructing fishing lures from metal alloys, such methodsmay be employed in combination with the compositions of the presentinvention. Methods of making radiological shielding devices and clothingor other apparel are well known to those of skill in the art.

The following examples are included to demonstrate preferred embodimentsof the invention. It should be appreciated by those of skill in the artthat the techniques disclosed in the examples which follow representtechniques discovered by the inventor to function well in the practiceof the invention, and thus can be considered to constitute preferredmodes for its practice. However, those of skill in the art should, inlight of the present disclosure, appreciate that many changes can bemade in the specific embodiments which are disclosed and still obtain alike or similar result without departing from the spirit and scope ofthe invention.

EXAMPLE I Material Testing

The material testing consisted of performing flexural three point bendtests on compression molded tungsten powder/polymeric binder flexuraltest bars and performing tensile tests on injection molded tungstenpowder (and stainless steel fiber) polymeric binder tensile test bars.The flexural testing was used to screen the large number of candidatepolymer mixtures and to select several optimal materials for injectionmolding. The tensile testing was performed to compare the materialproperties of each candidate injection molded composite mixture andlead.

Flexural Testing

Eleven candidate thermoplastic polymeric binders were successfully mixedwith tungsten powder in a Brabender mixer. Each polymeric binder wasmixed with the tungsten powder in a 50% volume ratio (25 cc of tungstenpowder and 25 cc of polymeric binder). The tungsten powder had an equaldistribution of particle sizes ranging from about 2 to about 20 microns.Each of the tungsten powder/polymeric binder mixtures was removed fromthe Brabender mixer and ground into particles using a laboratorygrinder. Each mixture was then compression molded into flexural testbars using a hydraulic compression molding machine. FIG. 1 shows apicture of compression molded tungsten powder/polymeric binder flexuraltest bars. One thermoset polymeric binder (TRI/Austin MDI/Polamine 1000formulation) was mixed with tungsten powder in a standard rotary mixerusing a 50% volume ratio. The tungsten powder thermoset polymeric bindermixture was placed into a flat plate compression mold. The mold was putinto a hydraulic compression molding machine and was allowed to cureovernight at room temperature under clamping pressure. Flexural testbars were punched from the flat plate using a flexural test bar stampingdie. All of the flexural test bars had the following dimensions; 2.5inch length by 0.5 inch width by 0.125 inch thickness. Table 3 providesthe average measured specific gravity for each of the polymeric bindersused. The flexural test bars had a specific gravity ranging from 10.00to 10.63.

TABLE 3 Specific Gravity of Compression Molded Tungsten powder/polymericbinder Flexural Test Bars Polymeric binder Specific GravityBiodegradable Cellulose (Planet Polymers 10.02 PT-C300ZT) ECTFEFlouropolymer (Ausimont Halar 5001LC) 10.63 Ethylene Interpolymer AlloyElastomer (DuPont 10.15 Alcryn 2070NC) Ethylene - Vinyl AcetateElastomer (DuPont Elvax 10.48 360) Ionomer (DuPont Surlyn 8220) 10.00Nylon 11 ® (Atochem BMFO) 10.10 Nylon 12 ® (EMS Grilamide L20GHS) 10.08Polytherimide (G.E. Ultem 1000) 10.43 Polyester Thermoplastic Elastomer(Bayer Texin 10.43 480-A) Polypropylene (AMOCO ACCTUF 3434) 10.15Polyvinylidene Flouride (Ausimont Hylar 461) 10.00 Thermoset Polyurea(TRI/Austin MDI/Polamine 1000 10.33 Formulation)

Six compression molded flexural test bars of each tungstenpowder/polymeric binder mixture from Table 3 were subjected to a threepoint bend flexural test. FIG. 2 shows a picture of the three point bendflexural test fixture and a flexural test bar installed in an Instrontesting machine. Each of the flexural bars was tested to failure using amodified ASTM D790 standard flexural test method. FIGS. 3 through 6present the results from the flexural testing. The test results indicatethat a wide range in flexural strength, displacement and modulus can beobtained by mixing different polymeric binders with tungsten powder. Theelastomeric polymeric binders (ALCRYN 2070NC, ELVAX 360, TEXIN 480A andthe polyurea thermoset) showed the most ductile behavior having thelowest flexural strength and modulus, and the highest flexuraldisplacement. The high melt temperature polyetherimide (ULTEM 1000)mixture had the highest flexural strength and modulus but exhibited abrittle behavior with a low flexural displacement. The Nylon12®(GRILAMIDE L20GHS) exhibited the second highest flexural strength andthe highest flexural displacement excluding the elastomeric polymericbinders, but had a relatively low flexural modulus. Since ductility andstrength are of paramount importance in cold forming tungstenpowder/polymeric binder projectile cores, the Nylon 12®(GRILAMIDEL20GHS) and polyester thermoplastic elastomer (TEXIN 480A) polymericbinders were selected for injection molding into tensile bars andprojectile cores.

Tensile Testing

Tungsten powder/polymeric binder mixtures using the Nylon 12®(GRILAMIDEg L20GHS) and polyester thermoplastic elastomer (TEXIN 480A) resins wereprepared in a Brabender mixer. 700 cc mixtures were prepared for eachpolymeric binder with a tungsten powder volume ratio of 54%. Thetungsten powder had evenly distributed particle sizes ranging from 2 to20 microns. An additional 700 cc mixture was also prepared for eachpolymeric binder by adding stainless steel fibers at a 10% volume ratioto the Nylon 12® tungsten powder/polymeric binder material. Each mixturewas removed from the Brabender mixer and ground into particles using agrinder. Table 4 shows the volume and weight ratios for each mixture.ASTM D638 Type V “dogbone” tensile test bars (2.5 inch length by 0.125inch width by 0.06 inch thickness) were injection molded from eachmixture using a Master Precision Mold Test Specimen Four Cavity mold.FIG. 12 shows a picture of the injection molded composite materialtensile test bars.

TABLE 4 Volume and Weight Ratios for Tensile Bar Composite MaterialsGRILAMIDE GRILAMIDE TEXIN 480A L20GHS Nylon 12 ® L20GHS Nylon 12 ®Polyester Elastomer with Stainless Steel Fiber Mixture Volume WeightVolume Weight Volume Weight Constituent Ratio (%) Ratio (%) Ratio (%)Ratio (%) Ratio (%) Ratio (%) Tungsten Powder 54.0 96.0 54.0 95.0 46.088.0 Polymeric binder 46.0  4.0 46.0  5.0 44.0 4.0 Stainless Steel Fiber— — — — 10.0 8.0

Six tensile bars of each mixture were tested using an Instron tensiletesting machine. The tensile tests were performed as per ASTM standardD638 test method. FIG. 7 shows a picture of a fractured tensile test barafter being pulled in the Instron tensile testing machine. FIGS. 8through 10 show the results from the tensile testing.

FIG. 8 compares the tensile strength of the composite projectile corematerials to lead. The Nylon 12®/tungsten powder/stainless steel fibercomposite had the highest tensile strength of the three compositematerials. The addition of stainless steel fibers increased the strengthof the Nylon 12® tungsten powder composite approximately 4.5% from 6,769to 7,074 psi. Both of the Nylon 12® composite materials had much highertensile strengths than lead, while the polyester elastomer composite wasapproximately one third of that of lead. FIG. 9 compares the elongationat break values. None of the composite materials showed elongationvalues as high as the 50% value for lead. The polyester elastomercomposite showed the most elongation of the composite showed the mostelongation of the composite materials tested with a value of 5.9%. FIG.10 presents the tensile modulus results for the composite materialsrelative to lead. The addition of stainless steel fiber provided an 8.6%improvement in tensile modulus from 974 to 1,058 ksi for the Nylon 12®composite material. The polyester elastomer had an extremely low modulusof 31.5 ksi compared to the 2,340 ksi modulus of lead.

The tensile test results show that Nylon 12® composite projectilepossess a superior tensile strength and have a reasonably high tensilemodulus compared to lead, but are much less ductile than lead. Theaddition of stainless steel fibers in the Nylon 12® composite materialsubstantially increases the tensile strength and modulus with negligiblereduction in ductility. The polyester elastomer was the most ductile ofthe composite materials, but had the lowest tensile strength andmodulus.

TPP binder composites with specific gravities in the range of 10 to 11may be formulated to produce a variation in physical properties,depending on the type of polymeric binder employed. Moreover, theincorporation of fibers, such as stainless steel fibers, into thetungsten powder/polymeric binder composite materials demonstrates animprovement in physical properties of the material.

Over 150 7.62 mm projectile cores with specific gravities ranging from10.2 to 11.0 were injection molded using tungsten powder and stainlesssteel fibers and mixed in a Nylon 12® and polyester elastomer polymericbinder.

EXAMPLE II Molding Projectile Materials

Projectile Materials

The polymeric binders, such as Nylon 12®, polyester elastomer, andpolyetherimide were compounded with tungsten powder in the ranges of 2to 4 microns, 4 to 8 microns and 20 to 40 microns, followed by physicalevaluation of composite. Larger particle sizes have less total surfacearea than smaller particle sizes for a given mass of tungsten powder,therefore it is possible to add more of the larger particle size powderwith the polymeric binder to produce a more dense TPP composite. Inaddition, fibers, such as stainless steel fibers, were added to thecomposite. Fibers may be added in volume ratios such as 10, 20, and 30%.The effect of fiber volume on the physical properties of the TPPcomposite is evaluated.

Injection Mold Specimens

Specimens may be injection molded from each of the TPP compositematerials compounded as above. Molding of tensile and impact bars may beaccomplished using, for example, the Master Precision Mold Test SpecimenFour Cavity Model injection mold. See FIG. 11. The mold produces thefollowing test specimens:

1. 0.04 inch thick by 2.5 inch diameter impact test disc;

2. 0.125 inch by 5.0 inch impact test bar;

3. 0.125 inch by 0.5 ASTM D638 Type I “dogbone”; and

4. 0.06 inch by 0.125 ASTM D638 Type V “dogbone”

FIG. 12 shows an injection molded TPP composite tensile bar. It iscontemplated that the methods of the present invention will be utilizedto mold ASTM D638 Type I “dogbone” tensile bars for tensile testing andimpact test bars will be molded to Izod impact testing.

Materials Properties Testing

Materials properties tests are performed on each selected candidate TPPcomposite material to evaluate the physical behavior of the material andto compare the material properties of the composite material to lead.These tests were used to screen TPP composite materials demonstratinginadequate physical properties performance, such as low specificgravity, low ductility, low impact strength or low tensile strength. Thephysical properties testing consists of determining the specificgravity, performing tensile and Izod impact tests, and thermal expansiontests on each of the candidate TPP composite materials. The averagespecific gravity of each material is calculated by measuring the massand volume of the tensile and impact bars injection molded as above.

Tensile Testing

Tensile testing has been performed on Nylon 12®, Nylon 12® with 10%stainless steel fibers, and polyester elastomer TPP composite materials.The tensile tests consisted of testing six ASTM D638 Type V tensile testbars of each TPP composite material in an Instron tensile testingmachine. FIG. 7 shows a picture of a fractured TPP composite tensiletest bar in the Instron testing machine. The average tensile strength,elongation at break and modulus were calculated for each material. FIGS.8-10 present representative tensile test results that may be used toassess the tensile properties of each material and compare these tensileproperties to lead.

Thermal Expansion Testing

The coefficient of thermal expansion is determined for each candidateTPP composite material. The thermal expansion is measured by attachingstrain gauges to impact test bars. The strain gauges are orientedparallel and perpendicular to the long axis of the bar to measure thethermal expansion in the flow and cross flow mold directions. Thetesting is performed in a temperature controlled environmental chamberand thermocouples are attached to the bar to accurately measuretemperature. An automated data acquisition system records both thetemperature and strain in real time during the test. The TPP compositethermal expansion results are compared to the coefficient of thermalexpansion for the copper jacket material to predict thermal stressesthat would be applied to the TPP composite projectile core by the copperjacket due to differential thermal expansion. The coefficient of thermalexpansion for copper is about 9.2 parts per million degree F., 2.55 fortungsten and 70 for Nylon 12®. Using the rule of mixtures, the estimatedcoefficient of thermal expansion for a tungsten powder/Nylon 12®composite with a specific gravity of 11.0 would be about 33.6 parts permillion degree F.

Injection Molded Projectile Cores

One method of making copper jacketed injection molded metal powderpolymeric binder composite projectile cores is to place the copperjacket into the injection mold and inject the metal powder polymericbinder composite material into the jacket cavity. The second andpreferred method is to injection mold the tungsten powder/polymericbinder projectile core, insert the molded projectile core into thejacket, and cold form both the core and jacket into the desired bulletgeometry.

FIGS. 29 and 30 are drawings of the 7.62 mm projectile core injectionmold. About 50 projectile cores were injection molded from each of themetal powder (and stainless steel fibers) polymeric binder compositemixtures shown in Table 4. FIG. 13 shows a picture of an injectionmolded projectile core, a lead projectile core, and a copper jacketedlead projectile core.

The single cavity 7.62 mm projectile core injection mold may be modifiedinto a multi-cavity mold to allow for more economical production oflarger quantities of TPP composite projectile cores. It is alsorecognized that high volume production projectile core injection moldsmay be utilized with the formulations of the present invention. Suchmolds, for example, may contain about 32 cavities.

Currently, a copper jacket is cold formed onto the core. While thismethod may be suitable for the present compositions, another method isto heat the projectile core above room temperature but below the meldtemperature of the polymeric binder (approximately 100 to 150 degreesC.) prior to insertion of the core onto the copper jacket. This ineffect would change the cold forming process into a hot (or warm)forming process. Because the polymeric binders are thermoplastics theywill become much more ductile at the warmer temperature allowing forimproved forming of the projectile core into the final desired bulletshape. The second method is to change the shape of the injection moldedcore to more closely resemble the final copper jacketed bullet shape.This allows the molded projectile core to be cold formed into the finalcopper jacketed bulled shape with less deformation of the TPP compositematerial.

EXAMPLE III Projectiles Cores

Projectile cores suitable for the present invention include but are notlimited to, for example, 5.56 mm, 9 mm, and .50 caliber ammunition. Alsosuitable are 7.62 mm and .45 caliber. FIGS. 26-28 are design drawingsfor 7.62 mm ammunition, and are used in design studies. Such designstudies identify appropriate TPP composite materials to use for eachtype of lead projectile core replacement.

Table 5 shows the average projectile core weight and specific gravity,and Table 6 shows the average dimensional measurements for the TPPcomposite projectile cores.

TABLE 5 Average Weight and Specific Gravity of Injection MoldedComposite Projectile Cores Average. Projectile Average. SpecificComposite Projectile Core Material Core Weight (g) Gravity Nylon 12 ® -Tungsten Powder 5.76 11.0 Polyester Elastomer - Tungsten 5.57 10.4Powder Nylon 12 ® - Tungsten Powder 5.25 10.2 with Stainless SteelFibers

TABLE 6 Composite Projectile Core Dimensional Measurements AverageDiameter Average Length Composite Projectile Core Material (inches)(inches) Nylon 12 ® - Tungsten Powder 0.240 1.26 Polyester Elastomer -Tungsten Powder 0.242 1.27 Nylon 12 ® - Tungsten Powder with 0.241 1.26Stainless Steel Fibers

Compression tests are performed by placing the projectile core on a flatplate in an Instron testing machine oriented vertically with the tip ofthe projectile core up. A second flat plate attached to the crosshead ofthe machine allows the projectile core to be compressed between the twoplates by the testing machine. The projectile core is tested to failure.A lead projectile core is also compression tested for comparison to theTPP composite cores, allowing a comparison between compressive strength,and modulus of each core.

FIG. 14 shows a vertical drop compressive impact test that provides aqualitative assessment of impact resistance for each of the TPPcomposite material projectile cores and lead projectile cores. Theprojectile core is placed in a stand mounted on a concrete floor. Animpact mass of 16.5 lb. is released from calibrated height positions of6, 12, and 18 inches. FIGS. 15-23 show side-by-side comparison picturesof each candidate TPP composite material compared to lead. A visualcomparison material showed the greatest impact resistance of thecomposite materials tested. This qualitative assessment indicates thatthe addition of stainless steel fibers substantially increases theimpact resistance of the Nylon 12® tungsten powder composite materials.The Nylon 12® composite material with and without stainless steel fibersappear to perform as well or better than the lead projectile cores(retain the same or more of their original shape) at each drop height.The lead projectile cores show more deformation than the Nylon 12®composite cores, but the Nylon 12® cores tend to shed material at higherimpact levels. The polyester elastomer projectile cores show about thesame deformation as the lead cores but fragment at all drop heights.

Ballistic testing of projectile cores is accomplished by testing thevelocity and pressure (ANSI/SAAMI method) from test barrels. Chamberpressure and velocity measurements are made simultaneously, andindividual values, mean values, extreme variation of individual values,and standard deviation are measured. Also measured is accuracy from testbarrels, bullet integrity and fouling, function and casualty ofammunition, penetration, and temperature stability.

Projectile Core Testing

Preliminary examination and testing was performed on the prototypeinjection molded projectile cores to compare their material behavior tothat of the lead cores. Visual examinations were made of sections ofprojectiles to determine if any voids or porosity problems existed. Noneof the examined projectiles showed any void or porosity problems.Dimensional measurements were made to determine the dimensionalstability of the tungsten powder/polymeric binder composite materials.Length and diameter measurements were made on randomly selectedprojectile cores from each of the projectile core composite materials.Table 6 presents the dimensional measurement results.

All three of the composite materials showed excellent dimensionalstability after injection molding. The diameter and length measurementswere consistent with only a 1 to 2 mils difference between individualprojectile cores. Each of the three composite materials had similardiameter and length measurements with the polyester elastomer havingslightly larger dimensions than the Nylon 12® composites. All of thematerials showed mold shrinkage having smaller dimensions than thedesign drawing specifications of 0.245 inches in diameter and 1.033inches in length. This indicates that the projectile core injection moldwill have to be adjusted accordingly once a final composite material isselected. The mass and volume of the injection molded projectile coreswere measured and the specific gravity of each composite materials wasdetermined. Table 5 presents the weight and specific gravity of thecandidate metal powder (and fiber) polymeric binder composite projectilecores.

Eleven thermoplastic injection moldable and two thermosetting polymerswere successfully mixed with tungsten powder producing projectile corecomposite materials with specific gravities ranging from 10.0 to 10.63.A wide range in physical properties was achieved depending on the typeof polymeric binder system employed. The tungsten powder/polymericbinder composite materials showed physical behavior ranging from brittleto highly ductile. The flexural strength of the composite materialsranged from 509 to 12,990 psi, the maximum flexural displacement rangedfrom 0.02 to 0.46 inches, and the flexural modulus ranged from is 16.2to 2,531 ksi.

Stainless steel fibers were successfully added to two tungstenpowder/polymeric binder composite projectile core materials to improvephysical properties and reduce cost. Both tensile bars and projectilecores were successfully injection molded using 46% by volume tungstenpowder and 10% by volume stainless steel fibers in a polymeric binder.

Tensile test results show that the Nylon 12® tungsten powder compositematerials possess the required tensile physical properties forprojectile core applications. The addition of stainless steel fibersproduced a significant increase in tensile strength and modulus of theNylon 12® tungsten powder composite material.

A qualitative assessment of vertical drop impact results showed that theNylon 12® tungsten powder composite materials with and without stainlesssteel fibers had equal or superior impact strength when compared tolead. The Nylon 12® tungsten composite material with stainless steelfiber showed the highest impact resistance of the composite materialstested.

Both tungsten powder/polymeric binder composites and tungsten powder andstainless steel fiber polymeric binder composite materials can be easilymixed together and injection molded using standard mixing and moldingequipment. No mixing problems were encountered with tungsten powdervolume ratios as high at 54% and a stainless steel fiber ratio of 10%.Visual examination of the molded projectile cores showed excellentsurface finish and no void or porosity problems were identified.Although no formal procedure was used to measure the balance of theprojectile cores, a visual examination of the sectioned cores showed theappearance of an even distribution of metal powder and fibers in thepolymer matrix.

EXAMPLE IV Tungsten/Nylon 12® and Tungsten/Nylon 12®/Stainless SteelComposites for Use as Projectiles: Bullet Assembly and Testing

Two composite materials were developed for use in projectile assembly asillustrations of the uses of the compositions of the present invention.These materials included a tungsten/Nylon 12® composite and atungsten/Nylon 12®/stainless steel composite. Stainless steel fibers(0.125″ long, 75 micron diameter) were used in the second composite toprovide a 4% increase in flexural strength and 8% increase in tensilemodulus. The process for manufacturing the materials consists of mixingeach component in a Brabender-type mixer and then grinding the materialsinto particles. The tungsten/nylon composite is ground much finer thanthe stainless steel composite which is left as a more coarse material soas not to damage the steel fibers. Once the materials are mixed, theyare put in a drier for 24 hrs. After the drying process, the material isfed into a hopper and injection molded to final shape. Cores were moldedby Gate Mold, Inc., Round Rock, Tex. Processing time for each slug wasapproximately 20 seconds. This time may be significantly reduced if amulti-cavity mold is used. In addition, the amount of waste material(material that cures while in the runner system) may also be eliminated,substantially reducing unit cost, if a hot runner system or valve-gatemold is used. However, this type of mold was not considered economicalfor the limited number of projectiles required for this evaluation.

TABLE 7 Candidate Projectile Materials COMPOSITE MANUFACTURERDESIGNATION MATERIALS Texas Research Inst. Non-Toxic Material #1Tungsten/Nylon 12 ® Texas Research Inst. Non-Toxic Material #2Tungsten/Nylon 12 ®/ Stainless Steel

Initial post mold quality control inspections of the cores yielded somesignificant findings. The cores manufactured by TRI demonstratedexcellent uniformity in terms of core length and diameter. However,there was significant amount of variation noted in the core weight.Average weights of both composites were below the 32±0.3 grainrequirement. The tungsten-Nylon 12® composite, although close to therequirement, averaged 31.3 grains while the tungsten-Nylon 12®-stainlesssteel composite was significantly lighter, averaging 27.5 grains. Partof the reason for the low weight was the core overall length, which,although consistent, was approximately 0.052 in. less than therecommended length due to post mold shrinkage. If the stainless steelcomposite cores were molded to the recommended length the correspondingweight would be 30.8 grains, much closer to meeting the requirement. Theprimary cause for the variation in weight, however, was the use ofregrind material during the molding process. Regrind material comes fromthe excess material which cures in the runner system of the mold foreach part produced. This excess is then reground, mixed, andreintroduced into the molding process. During this process the physicalproperties of the nylon, such as density, are altered significantly,resulting in variations in the final product. Both of the problems notedwith these cores (length and weight) may easily be corrected. Bymodifying the mold cavity, overall length may be increased as required,and by using only virgin nylon material, the variation in weight will bereduced or eliminated. Also, if a mold with a hot runner system or avalve-gate type mold were used, although initially more expensive, wouldhelp to eliminate any excess (waste) material during the moldingprocess. However, if these cores are to be recycled, the tungsten andnylon may be separated and only the tungsten re-used. Inspection resultsfor both core materials are shown in FIG. 30A, FIG. 30B and FIG. 30C.

Table 8 shows a comparison of the average measured weights anddimensions for each sample as compared to the dimensions shown on thecore drawing. The Score Factor in the far right column is a cumulativetotal of the percentage difference between the average sample dimensionand the corresponding drawing (requirement) dimension. Therefore, thelowest scoring factoring represents the closest similarity to thedesired weight and dimensions.

TABLE 8 Core Dimensional Characteristics SCORE *DIA. *LENGTH WEIGHT FAC-MATERIAL (in.) (in.) (grams) TOR Requirement 0.180 0.510 2.074 ± 0.019Average Measurements Lead (Control) 0.175 0.503 2.067 16.8 Non-ToxicMaterial #1 0.181 0.457 2.026 13.3 Non-Toxic Material #2 0.181 0.4591.789 24.3 *Length and diameter are given as basic dimensions. Finalconfiguration is determined by core weight.

Bullet Assembly

One-thousand (1,000) 5.56 mm M855 projectile cores manufactured fromeach of the materials described above were delivered to Lake City ArmyAmmunition Plant in June 1996. These cores were assembled into 5.56 mmcartridges. Assembly included jacketing the cores, forming the bullets,and loading into cartridge cases. Assembly was conducted on aWaterbury-Farrel Bullet Assembly Machine (BAM) currently being used forM855 projectile production. Core samples were initially hand fed and theBAM adjusted until a dimensionally correct bullet was produced. Theremaining cores were then put into the hopper and fed automatically intothe assembly process. Samples of assembled bullets were randomlycollected and inspected for weight and dimensions throughout theassembly process.

Another sample used was the tungsten-nylon composite, TRI#1, developedby the inventors. No adjustments were made to the BAM from the previoussample. This sample ran exceptionally well, meeting all dimensionalrequirements while presenting no feed or assembly problems. The TRI#2sample, the tungsten-nylon-stainless steel composite, was then used.Again, no adjustments were made to the BAM and no feed or assemblyproblems were encountered. Bullets met all dimensional requirements,however, the weight of the TRI#2 samples were approximately 3-4 grainsbelow the requirement.

Upon completion of bullet assembly, a 10% inspection was performed on arandom sample taken from each lot. Bullets were weighed and measured foroverall length, boattail length, diameter, ogive profile, cannelurelocation, point diameter, boattail profile, as well as point andboattail concentricity.

The TRI#1 samples showed a higher degree of weight variation. With theTRI#1, 7% of the inspected parts weighed 60.2 grains, 0.1 grains belowthe minimum weight while the TRI#2 sample had only 5% withinrequirements. The remainder of the latter sample fell below the minimumweight, averaging 58.2 grains which was expected due to the use ofregrind material during the molding process.

Overall length measurements revealed that samples of each materialcontained between 6 to 21 parts that were 0.0005″ to 0.005″ above theoverall length requirements. Boattail lengths on the other hand were allwithin Government control limits, with each sample showing about as muchvariation as the control. Other dimensional characteristics such asdiameter, ogive and boattail profile, cannelure location, and pointdiameter typically are measured with various go/no go gauges. Uponinspection, 100% of each sample met the ogive profile and cannelurelocation requirements.

A summary of the weight and dimensional characteristics are shown in theTables below. Again, the score factor shown at the bottom of each tableis the cumulative total of the percentage difference between the averagemeasured dimension and the corresponding drawing dimension. In Table 9,the average values for point and boattail concentricity were added tothis cumulative total since the desired concentricities are 0.0 in. andnot the values shown in parentheses, which represent the acceptablemaxima. In Table 4, only a go/no-go criteria was used during theinspection. The percentage of samples of each material that fell in theno-go category is shown. As before, the lowest score factor representsthe closest similarity to the desired weight and dimensions.

TABLE 9 Inspection Results Dimensions TRI #1 TRI #2 Control Weight61.700 58.200 62.400 (61.8 ± 1.5 grains) Over-All Length 0.916 0.9140.908 (0.923-0.030 in.) Length of Boattail 0.106 0.106 0.107(0.110-1.010 in.) Point Concentricity 0.004 0.003 0.004 (0.005 in.)Boattail Concentricity 0.001 0.000 0.000 (0.003 in.) Score Factor 5.0610.73 5.72

TABLE 10 Fixed Gage Inspection Results Percentage of Sample Out ofSpecification Limits Characteristics TRI #1 TRI #2 Control Diameter 3153 0.0 (0.2245-0.0006 in.) Ogive Profile 0.0 0.0 0.0 Cannelure Location0.0 0.0 0.0 (0.485-0.010 in.) Point Diameter 2 3 7 (0.040-0.022 in.)Boattail Profile 100 100 0.0 (0.2245-0.0006 in.) Score Factor 1.33 1.560.07

Cartridge Loading

Prior to final cartridge loading, a sample of 15 cartridges were loadedusing each core type to confirm that the selected charge weights wouldbe effective under the production assembly conditions. This is standardprocedure for all loading operations. After the initial pre-load,pressures and velocities were found to be high. Charge weights were thenadjusted and a second pre-load showed the pressures and velocities to beacceptable. All bullets were then assembled into M855 cartridges usingthe standard plate loading equipment and M855 cartridge cases. WC844propellant, lot 49924, was used for the entire loading operation.Pre-load and final charge weights are shown below.

TABLE 11 Propellant Charge Weights Propellant: WC844, Lot 49924 Primer:Lot LC96D704-435 Propellant Charge Weights (Grains) Projectile Hand Load1st Pre-Load 2nd (Final) Pre-Load TRI #1 27.5 27.5 27.3 TRI #2 27.3 27.327.1 Control 27.2 27.2 None Fired

Upon completion of loading, all cartridges were subjected to a 100% gageand weigh inspection. This includes weighing each cartridge, measuringoverall length, and measuring head to shoulder length. The inspectionshowed no defects with the TRI#1 composite. Inspection of the TRI#2composite showed approximately 50% of the cartridges to be under weight,which was due to the low projectile weight. Ten cartridges of each typewere also weighed on an electronic scale for weight verification.

Test Program

Cartridges made from lead and each of the composites TRI#1 and TRI#2were then subjected to a series of tests to assess the interior,exterior and terminal ballistic performance of each material candidate.Throughout Phase I, the current 5.56 mm M855 cartridge was used as thebaseline (control or reference) for assessing performance. Testing wasconducted at three locations: Lake City Army Ammunition Plant, NavalSurface Warfare Center, Crane, and the Armament Technology Facility(ATF), Picatinny Arsenal. Testing conducted by LCAAP included ElectronicPressure, Velocity and Action Time (EPVAT) as well as dispersion at a600 yard range. Both of these tests were conducted at hot (+125° F.),cold (−65° F.), and ambient (70° F.) temperatures. EPVAT testing wasused to identify the pressures the projectiles were subjected to whenlaunched from a gun tube as well as the corresponding velocitiesachieved while dispersion testing provided a true indication of theperformance of the rounds in terms of stability during flight anduniformity during manufacture.

Electronic Pressure, Velocity and Action Time Test

Results of the EPVAT test are shown in Table 12®. Data obtained fromthis test included casemouth pressure, port pressure (the pressure at amid-point in the barrel comparable to the gas port location on automaticweapons), velocity at 78 ft from the muzzle, and action time which isthe time from primer indent to when peak port pressure is obtained. BothTRI composites met all the requirements for pressure, velocity andaction time at each of the three temperatures. It is also interesting tonote that the TRI#2, which had the largest weight variation,demonstrated a velocity variation similar to that obtained with thecontrol sample. In addition to recording pressure and velocity, arolling witness paper, which was scrolled after each shot, was placed 25ft. in front of the weapon in order to record any instances ofprojectile break-up or yaw. Throughout the test there was no evidence ofprojectiles yawing or becoming unstable. This indicates that the thermalexpansion and contraction of the materials at the extreme temperaturesis negligible. Also, the TRI composites showed no evidence ofprojectile/core break-up.

TABLE 12 EPVAT Test Results CASEMOUTH PORT VELOCITY @ ACTION PRESSUREPRESSURE 78′ TIME SAMPLE (psi) (psi) (fps) (mS) Requirement Ambient55,000 (max) 13,000 (min) 3,000 ± 40 3.0 (max) Hot/Cold <7,000 psi var.12,700 (min) <250 fps var. from amb. avg. from amb. avg. TRI #1 (Averageof 20 rounds fired at each temperature) Ambient 49,531 13,861 3,0210.897 Hot 53,592 14,215 3,103 0.883 Cold 44,192 13,461 2,880 0.932 TRI#2 (Average of 20 rounds fired at each temperature) Ambient 46,86413,752 3,009 0.892 Hot 49,984 14,140 3,089 0.884 Cold 42,464 13,3402,860 0.937 Control (Average of 20 rounds fired at each temperature)Ambient 48,927 13,584 3,008 0.891 Hot 54,105 13,816 3,101 0.870 Cold43,427 13,029 2,866 0.933

Dispersion Testing

Dispersion tests were then conducted using a M700 receiver and twoaccuracy barrels mounted in a v-slide. Each of the barrels hadapproximately 1,250 rounds fired prior to this test and were qualifiedwith M855 reference ammunition. Two record targets consisting of 10rounds each were fired from each barrel at ambient, hot (+125° F.), andcold (−65° F.) temperatures with both TRI samples and the controlsample. Ammunition was temperature conditioned for 4 hours prior tofiring. Weather conditions were clear, approximately 53° F. with 3 to 8mile per hour winds. After qualifying the barrels, each of the four testsamples were fired, followed by the control sample. This procedure wasfollowed at each temperature. The control lot was fired last to serve asa final check to assure there were no equipment malfunctions during thecourse of fire. Requirements for M855 dispersion testing state that thehorizontal and vertical standard deviation must be less than 6.0 in. fora 30 round target fired at a 600 yard range. For this test however, 10round targets were fired instead of 30 round targets due to theavailability of cartridges. A comparison was then made between each ofthe sample cartridges and the regular M855 cartridges to assess theperformance of each prototype. After firing was completed, resultsobtained with each barrel were averaged separately (Tables 7 through 9)and then combined to obtain an overall average. These overall values,shown in Tables 10 through 12 were then used as the basis forcomparison. The score factors shown in these tables were determined bycalculating the percent difference between the best performer and eachother sample. In this case, the best performer was whichever sampleshowed the smallest dispersion in the category being evaluated. Thesecategories included mean radius, horizontal standard deviation, verticalstandard deviation, and extreme spread at each of the threetemperatures. Results obtained at each temperature were then combined inorder to identify the best overall performer. This was accomplished byadding the score factors calculated at each temperature (Table 19). Eachsample was then ranked according to this final score with the lowestscore receiving the highest ranking. It is interesting to note that bothTRI samples which showed the largest dimensional variation duringmanufacture, also exceeded the performance of the standard M855cartridges. More importantly, the extreme temperatures (−65° F. and+125° F.) had no significant effect on the performance of the samples.This would indicate that the thermal expansion or contraction of thecores was not enough to adversely affect the fit between the core,jacket, and penetrator.

TABLE 13 600 YARD AMBIENT TEMPERATURE DISPERSION RESULTS MEAN HORIZ.VERT. EXTREME NO. RDS. RADIUS DEV. DEV. SPREAD SAMPLE FIRED (in.) (in.)(in.) (in.) TRI#1 Barrel 352420 10 5.56 4.30 5.47 21.85 10 7.38 7.354.60 23.70 Average: 6.47 5.82 5.03 22.77 Barrel 352723 10 5.01 5.11 2.9316.25 10 6.44 4.90 5.27 17.35 Average: 5.73 5.01 4.10 16.80 TRI#2 Barrel352420 10 7.45 7.28 4.17 22.45 10 6.84 5.58 5.25 20.00 Average: 7.156.43 4.71 21.22 Barrel 352723 10 6.79 4.43 6.29 10 7.56 4.97 7.09 24.25Average: 7.18 4.70 6.69 Control Barrel 352420 10 9.82 7.60 8.63 29.55 104.86 4.06 4.38 16.30 Average: 7.34 5.83 6.49 22.92 Barrel 352723 10 7.274.51 7.42 25.15 10 6.72 5.27 6.96 27.95 Average: 6.99 4.89 7.19 26.55

TABLE 14 600 YARD HIGH TEMPERATURE (+125° F.) DISPERSION RESULTS MEANHORIZ. VERT. EXTREME NO. RDS. RADIUS DEV. DEV. SPREAD SAMPLE FIRED (in.)(in.) (in.) (in.) TRI#1 Barrel 352420 10 8.20 8.61 4.90 30.30 10 9.377.31 7.23 24.10 Average: 8.78 7.96 6.07 27.20 Barrel 352723 10 5.22 4.094.33 14.35 10 5.30 5.42 2.93 17.20 Average: 5.26 4.76 3.63 15.77 TRI#2Barrel 352420 10 10.32 8.29 8.52 30.15 10 5.74 5.07 4.01 15.55 Average:8.03 6.68 6.27 22.85 Barrel 352723 10 4.89 4.05 3.85 15.10 10 5.49 4.714.42 10.85 Average: 5.19 4.38 4.14 12.97 Control Barrel 352420 10 11.6413.20 7.03 45.65 10 14.64 8.93 15.44 46.45 Average: 13.14 11.06 11.2346.05 Barrel 352723 10 7.38 7.15 5.00 23.30 10 7.86 6.46 5.97 21.00Average: 7.62 6.80 5.48 22.15

TABLE 15 600 YARD COLD TEMPERATURE (−75° F.) DISPERSION RESULTS MEANHORIZ. VERT. EXTREME NO. RDS. RADIUS DEV. DEV. SPREAD SAMPLE FIRED (in.)(in.) (in.) (in.) TRI#1 Barrel 352420 10 8.10 7.38 7.57 31.75 10 7.906.80 6.10 22.35 Average: 8.00 7.09 6.84 27.05 Barrel 352723 10 7.40 5.736.73 25.05 10 3.72 3.44 2.60 10.75 Average: 5.56 4.59 4.67 17.90 TRI#2Barrel 352420 10 7.09 5.54 6.07 22.75 10 5.15 4.67 4.84 21.60 Average:6.12 5.10 5.46 22.17 Barrel 352723 10 5.67 3.56 5.77 20.30 10 6.91 5.386.08 21.70 Average: 6.29 4.47 5.92 21.00 Control Barrel 352420 10 6.586.11 4.14 18.80 10 7.53 6.24 6.26 23.55 Average: 7.06 6.17 5.20 21.17Barrel 352723 10 6.58 3.45 7.IO 24.50 10 8.50 7.20 5.97 20.80 Average:7.54 5.33 6.54 22.65

TABLE 16 CUMULATIVE AMBIENT TEMPERATURE DISPERSION RESULTS MEAN HORIZ.DEV. VERT. DEV. SCORE SAMPLE RADIUS (in.) (in.) (in.) FACTOR TRI #1 6.105.41 4.56 4.03 TRI #2 7.16 5.56 5.71 4.59 Control 7.16 5.36 6.84 4.82

TABLE 17 CUMULATIVE HIGH TEMPERATURE DISPERSION RESULTS MEAN HORIZ. DEV.VERT. DEV. SCORE SAMPLE RADIUS (in.) (in.) (in.) FACTOR TRI #1 7.02 6.364.85 3.36 TRI #2 6.61 5.53 5.20 3.20 Control 10.38 8.93 8.35 5.12

TABLE 18 CUMULATIVE COLD TEMPERATURE DISPERSION RESULTS MEAN HORIZ. DEV.VERT. DEV. SCORE SAMPLE RADIUS (in.) (in.) (in.) FACTOR TRI #1 6.79 5.845.75 3.69 TRI #2 6.20 4.78 5.69 3.33 Control 7.30 5.75 5.84 3.77

TABLE 19 Overall Dispersion Test Results CUMULATIVE SCORE FACTORS SAMPLEAMBIENT HOT COLD TOTAL RANK TRI #1 4.03 3.36 3.69 11.08 2 TRI #2 4.593.20 3.33 11.12 3 Control 4.82 5.12 3.77 13.71 5

Terminal Ballistic Testing

The Naval Surface Warfare Center, Crane, Ind., conducted testing toassess the terminal performance of the cartridges incorporating TRI#1and TRI#2 composites against simulated hard and soft targets. Dataobtained from these tests was used to identify any shortfalls orimprovements of the candidate cartridges as compared to the standardM855 cartridge. The terminal ballistic tests conducted included thefollowing:

Soft Targets

1) 20% Ballistic gelatin at 10 meters

2) 20% Ballistic gelatin at 300 meters

3) 20% Ballistic gelatin behind auto glass at 300 meters

4) 20% Ballistic gelatin behind auto glass (45 degrees obliquity) at 300meters

5) 20% Ballistic gelatin behind a PASGT vest at 300 meters

Hard Targets

1) Determine R50 range against 12.7 mm aluminum plate

2) Determine R50 range against 3.5 mm NATO plate

3) Kevlar® Helmets at 1,000 meters*

4) 8″ concrete blocks at 100 meters

* Test was conducted at 50 meters with downloaded cartridges.

Ballistic Gelatin at 10 Meters

Soft target testing against 20% ballistic gelatin blocks positioned at10 meters from the weapon was conducted with each sample. Prior totesting, blocks were temperature conditioned to 50° F. for 36 hours andcalibrated using the BB penetration criteria. This criteria states thata .177 caliber BB at a velocity of 595±15 fps should penetrate the blockto a depth of 1.5±0.25 in. The weapon used for the test was a M16A2-E3rifle which was shoulder fired. Velocity for each round fired wasrecorded at a distance of 15 ft. from the muzzle. After firing each testround, penetration depth as well as the length and height of thetemporary cavity were measured. Four valid rounds of each cartridge typewere fired. A round was considered valid if the projectile fragments andthe entire cavity were contained within the block and did not contactthe cavity formed from a preceding shot. These measurements areillustrated in FIG. 31.

Results showed the TRI#1 cartridges most closely matched the performanceof the reference M855 cartridge in terms of cavity dimensions while theTRI#2 provided the closest match in terms of penetration depth. TheTRI#1 and TRI#2 samples averaged 13.4 in. and 12.2 in of penetration,respectively. Score factors were determined by totaling the averagevalues for penetration depth and cavity dimensions and then calculatingthe percent difference between the largest total and totals for theremaining samples. This method assumes that the largest cavitydimensions indicate the best performance.

TABLE 20 10 Meter Ballistic Gelatin Test Results Temporary Cavity Vel @Max. Max. 15 Ft. Penetration Dia. Depth Score Sample Rd No. (fps) Depth(in.) (in.) (in.) Factor TRI#1 1 3081 13.9 4.2 8.0 2 3098 15.4 4.4 8.2 33080 14.5 5.0 5.5 4 3074 9.8 5.2 7.3 AVG: 3083 13.4 4.7 7.2 1.19 TRI#2 13041 13.0 5.8 7.8 2 3090 10.8 5.4 7.0 3 3059 12.5 6.0 8.7 4 3025 12.46.2 8.4 AVG: 3054 12.2 5.8 7.9 1.16 Lead 1 3073 12.9 5.0 6.5 2 3070 9.04.7 7.0 3 3085 11.9 5.1 6.8 4 3104 12.4 5.0 8.1 AVG: 3083 11.5 4.9 7.11.28 *Bullet core broke skin of gelatin at back end of block

Ballistic Gelatin at 300 Meters

This test was conducted in the same manner as the 10 meter gelatin testwith the exception of the target range which was increased to 300meters. In addition, this test consisted of only three valid rounds percartridge type and projectile velocity was obtained with a WEIBELDoppler Radar system. Results of the test are shown below in Table 21.

TABLE 21 300 Meter Ballistic Gelatin Test Results Vel @ Impact TemporaryCavity 15 Ft. Vel. Penetration Max. Dia. Max. Depth Score Sample Rd No.(fps) (fps) Depth (in.) (in.) (in.) Factor TRI#1 1 3068 2162 13.2 3.48.3 2 2999 2153 14.5 3.0 5.8 3 3013 2769 16.3 3.6 7.9 AVG: 3027 236114.6 3.3 7.3 1.11 TRI#2 1 3038 2003 12.0 2.7 8.0 2 3027 2040 12.0 2.78.7 3 3037 2143 14.5 3.5 5.2 AVG: 3034 2062 12.8 3.0 7.3 1.21 Lead 13040 2129 15.8 4.0 8.0 2 3045 2082 16.3 3.5 8.5 3 3070 2177 15.6 3.8 8.1AVG: 3052 2129 15.9 3.8 8.2 1.00

Ballistic Gelatin at 300 Meters Protected by PASGT Vest

This test was conducted in the same manner as the 300 meter gelatin testwith the addition of a PASGT Kevlar® vest which was positioned directlyin front of the gelatin block. The results of this test are summarizedbelow in Table 22. In this test, the maximum average penetration depthof the lead core projectile was met or exceeded by each of the samplestested.

TABLE 22 Ballistic Gelatin Protected w/ PASGT Vest @ 300 m Vel @ ImpactTemporary Cavity 15 Ft. Vel. Penetration Max. Dia. Max. Depth ScoreSample Rd No. (fps) (fps) Depth (in.) (in.) (in.) Factor TRI#1 1 29762076 12.8 3.4 3.5 2 2990 2091 13.8 3.3 4.7 3 2994 2097 14.0 4.4 6.4 AVG:2987 2088 13.5 3.7 4.9 1.13 TRI#2 1 3017 2102 12.0 2.0 5.0 2 3028 217313.6 2.0 6.5 3 3019 2174 13.0 2.5 8.0 AVG: 3021 2150 12.9 2.2 6.5 1.17Lead 1 3031 2097 11.0 4.3 4.1 2 2988 2053 14.5 4.0 10.6 3 3001 2086 13.32.7 4.1 AVG: 3007 2079 12.9 3.7 6.3 1.09

Auto Glass (0° Obliquity) with Ballistic Gelatin at 300 meters

The purpose of this test was to document the effects of automobilewindshield glass on bulled integrity and penetration depth. Initially,the glass was positioned at a range of 300 meters at 0 degreesobliquity, or perpendicular to the line of fire. The windshieldconsisted of single layer autoglass, 0.219″ thick. In addition, agelatin block was placed 18 in. behind the glass. Three valid roundswere fired with each cartridge type. For this test, a round wasconsidered valid when the point of impact was not less than 2.5 in fromanother bullet impact and the temporary cavity did not impact any partof a cavity formed from a previous round. Results of this test aresummarized in Table 23. The TRI#1 samples achieved the greatestpenetration depth while the cavities produced by the lead projectileswere slightly larger than the cavities produced whith the other samples.It was also noted that one or two projectiles of each type fragmentedupon impact with the glass. Cavities in the gelatin block were thenbased on the impact of these fragments.

For the second part of this test, the auto glass was repositioned at 45degrees obliquity (top of the glass tilted away from the muzzle).Results of this test are summarized in Table 24. In this test, the TRI#1sample achieved the greatest penetration depth, followed closely by thelead projectiles. The TRI#1 and lead projectiles also produced thelargest cavities of all the samples tested. In addition, all of theprojectiles tested fragmented upon impact with the glass. In oneinstance the TRI#2 sample fragmented into numerous pieces and could notbe recovered.

TABLE 23 Auto Glass (0° Obliquity) with Ballistic Gelatin at 300 metersVel @ Impact Temporary Cavity 15 Ft. Vel. Penetration Max. Dia. Max.Depth Score Sample Rd No. (fps) (fps) Depth (in.) (in.) (in.) FactorTRI#1 1 3011 2006 11.0 2.5 6.2 2 3088 2085 10.4 2.5 8.0 3 3007 1997 11.52.0 9.0 AVG: 3035 2029 11.0 2.3 7.7 1.12 TRI#2 1 2995 2016 8.0 2.0 6.0 23021 2023 7.5 2.5 6.5 3 3010 1985 9.3 2.5 8.5 AVG: 3009 2008 8.3 2.3 7.01.34 Lead 1 2981 2015 10.4 4.0 8.5 2 3017 2055 10.0 3.0 8.0 3 3058 206212.0 2.5 10.0 AVG: 3019 2044 10.8 3.2 8.8 1.03

TABLE 24 Auto Glass (45° Obliquity) with Ballistic Gelatin at 300 metersVel @ Impact 15 Ft. Vel. Penetration Max. Dia. Max. Depth Score SampleRd No. (fps) (fps) Depth (in.) (in.) (in.) Factor TRI#1 1 3004 2048 5.23.0 4.0 2 3002 2065 6.0 3.5 4.5 3 3042 2057 9.0 2.7 6.0 AVG: 3016 20576.7 3.1 4.8 1.00 TRI#2 1 3021 1963 5.0 2.0 3.5 2 3011 2006 4.7 1.4 3.5 33019 1996 AVG: 3017 1988 4.8 1.7 3.5 1.46 Lead 1 3021 2069 6.0 4.0 5.0 23021 2041 5.7 2.2 5.0 3 3028 2056 6.0 2.4 5.3 AVG: 3023 2055 5.9 2.9 5.11.05

R50 vs. 12.7 mm Aluminum Plate

Set-up for this test included a 5.56 mm accuracy barrel and RemingtonM700 receiver mounded in a v-slide. The target plate was rigidly mountedat 0 degrees obliquity to the weapon. A Doppler radar tracking systemwas also used to record projectile velocity, acceleration, and time offlight from the muzzle to target. For this test, Army penetrationcriteria was used which states that any cracking of the target platequalifies as a complete penetration. Initial results showed all samplesachieved complete penetration (CP) of the target at 350 meters so thetarget was repositioned at 355 meters. At this range, the TRI#1 sampleachieved 5 CPs for 5 rounds fired whiled the M855 cartridge achieved 3CPs for 6 rounds fired. The target was then moved back to 360 meters. Atthis range, the TRI#2 sample had no CPs after four rounds fired. TheTRI#1 samples achieved CPs for 6 rounds fired. The target plate was thenmoved back to 365 meters where the TRI#1 sample achieved 2 CPs for 6rounds fired. Based on these results, the R50 range for each sample wasdetermined. The TRI#2 and M855 cartridges each achieved an R50 range of355 meters. The TRI#1 sample had the greatest R50, 363 meters. Muzzlevelocity and V50 velocity, which is the impact velocity at the R50 rangewere also determined for each sample. Results of this test are shownbelow in Table 25. The score factors in the right side column weredetermined by calculating the percentage difference between the farthestR50 range (363 meters for the TRI#1 sample) and the R50 range for eachother sample. As in the previous tables, the lower sore factor indicatesbetter performance.

TABLE 25 R50 vs. 12.7 mm Aluminum Plate Muzzle V50 Velocity SampleVelocity (fps) (fps) R50 Range (m) Score Factor TRI #1 3047 1963 3631.00 TRI #2 3056 1910 355 1.02 Lead 3060 2004 355 1.02

R50 vs. 3.5 mm Mild Steel Plate

The set-up and equipment used for this test was the same as used for theprevious test against the aluminum plate. The target plate wasoriginally positioned at 600 meters from the weapon. Cartridges werethen loaded and fired single shot. After each shot the target wasinspected and the shot was determined to be valid or invalid. To beconsidered valid, a shot had to hit the plate not less than 1 in. fromthe nearest hole, support, or edge of the plate. For each valid shot,the penetration, either full or partial was assessed. This procedure wasrepeated with each sample. After firing the test rounds, the targetrange was increased until the R50 range was established. Again, thescore factors in the right side column were determined by calculatingthe percentage difference between the farthest R50 range and the R50range for each other sample. As in the previous tables, a lower scorefactor indicates better performance.

TABLE 26 R50 vs. 3.5 mm Mild Steel Plate Sample R50 Range Score FactorTRI #1 710 m 1.25 TRI #2 620 m 1.43 Lead 680 m 1.30

Concrete Block Penetration

The objective of this test was to compare the penetration performance ofthe test cartridges when fired into concrete blocks positioned at arange of 50 meters from the weapon. Targets consisted of regular 2-coreconcrete blocks rigidly mounted on top of a target platform. Blocks wereheld in place with a ¼″ steel bracket positioned over the block andbolted to the platform. Six valid shots (2 per block) were fired witheach type of cartridge. A shot was considered valid if it impacted acore not previously shot and the bullet was more than 1.5 in. from theedge or center of the block. Each of the test cartridge samplescompletely penetrated the front wall of the target. The only projectilesto completely penetrate the block were the standard lead projectile; 2of the 6 rounds fired achieved complete penetration. On average TRI#2sample produced the least damage.

Kevlar® Helmet Penetration at 1,000 Meters

This test was conducted to compare the performance of the testprojectiles and standard projectiles when fired at Kevlar® lined combathelmets at a range of 1,000 meters. For this test however, targets werepositioned at a reduced range of 50 meters in order to increase the hitprobability and reduce the number of rounds required for this test.Cartridges were then downloaded to simulate the 1,000 meter velocity ata 50 meter range. It was determined that the 5.56 mm M855 type bulletwould have a residual velocity of approximately 261 mps (856 fps). Toachieve this velocity, cartridges were loaded with 3.8 grains ofBullseye powder. However, due to the large amount of free case volumeresulting from the reduced propellant load, projectile velocities showedslightly more variation than the standard cartridges. Five valid roundsof each type were then fired at the helmet. One round of each sample wasfired at the front, top, back, left side, and right side of the helmet.Impact velocities for each of the samples were within 3.5% of thedesired velocity of 261 mps. Overall, the TRI#1 and TRI#2 samplesachieved the best results, penetrating the helmet at each of the fiveorientations. The lead projectiles on the other hand, achievedpenetration on only 3 of 5 shots even though all impact velocities werewithin 3.5% of the desired velocity.

TABLE 27 Kevlar ® Helmet Penetration at 1,000 Meters Point of MuzzleVelocity Impact Velocity Complete Sample Impact (mps) (mps) PenetrationTRI #1 Top 281 271 Yes Back 265 254 Yes Rt. Side 266 253 Yes Lft. Side252 243 Yes Front 272 260 Yes AVG: 267 256 TRI #2 Top 277 268 Yes Back278 268 Yes Rt. Side 262 252 Yes Lft. Side 292 278 Yes Front 270 260 YesAVG: 276 265 Lead Top 280 270 Yes Back 276 265 Yes Rt. Side 268 260 NoLft. Side 279 267 Yes Back 262 252 No AVG: 273 263

Soft Recovery Test

This test was conducted to obtain information on the condition of theprojectiles after being fired into a simulated target berm. The targetberm in this case consisted of sandbags which were positioned 100 metersfrom the gunner. A witness panel was placed behind the sand bags todetermine if the projectiles completely penetrated the sand bags. Afterfiring 15 to 20 rounds into the berm, the sand was sifted through ascreen and the projectile fragments were recovered and photographed. Newsandbags were used for each sample tested.

The TRI#1 and TRI#2 cores did not demonstrate the same high degree offragmentation after impact. A larger percentage of these cores wererecovered both within the jackets and in pieces separate from thejackets. The TRI#2 cores demonstrated the least amount of frangibilityof all the samples. Several samples of these cartridges were recoveredwhile reasonably still intact.

Lead projectile fragments consisted primarily of jacket pieces and leadchunks which most closely resembled the TRI#1 fragments. The table belowshows the average weight of the seven largest recovered core fragmentsof each type. The TRI#2 projectiles, on average, retained the largestmass of all the samples tested. Although this test was conducted with alimited number of rounds under tightly controlled conditions, this maybe an indication of how easily recoverable the materials will be forrecycling purposes. A mass comparison of the recovered projectilefragments is shown in Table 28.

TABLE 28 Average Mass of Recovered Projectile Fragments (Grains) AverageMass of Recovered Fragments Sample (Grains) Score Factor TRI #1 29.41.68 TRI #2 49.4 1.00 Lead 37.9 1.31

Toxic Fumes Test

Toxic fumes testing was conducted at the ARDEC Armament TechnologyFacility. This test assessed the gaseous and particulate emissions fromthe cartridges when fired. For this test, an M16A2 rifle was mounted ina hard stand enclosed in a sealed chamber. Five firing trials wereconducted using each of the five cartridge samples. For each trial, 30rounds of ammunition were loaded into the magazine and fired in ten3-round bursts with 3-5 seconds between bursts. Gas and metalconcentrations were monitored during the firing and for a 30-minuteperiod after the firing of each trial was completed. Sampling pointswere located 6 in. to the left and right of the buttstock as well asdirectly behind the buttstock. These locations, which are illustrated inFIG. 32, were chosen to simulate the position of the gunner's head whilefiring. Particulate concentrations were then compared to the Maximumthreshold limit values (MTLV) as determined by the American Conferenceof Government Industrial Hygienists.

Preliminary analytical data showed some significant findings. First ofall, the lead emissions from each of the four test cartridge sampleswere reduced to approximately one half that of the standard servicecartridge. The MTLV for lead is 0.05 mg/m³. Results showed the leadconcentrations from the service cartridges averaged approximately 0.5mg/m³, 10 times the MTLV. The concentrations emitted from the testcartridges averaged approximately 0.25 mg/m³. Although this stillexceeds the MTLV, there is a noticeable reduction of lead emissions.Also, silica, which is a primary component of the nylon used in the TRIsamples, was detected at concentrations of less than 1% of the MTLV.Laboratory data also showed that concentrations of sulfur dioxide, iron,and nickel fell well below the MTLV for each sample.

Non-Lead Core Materials Evaluation Conducted by Department of Energy—OakRidge National Laboratory (ORNL)

The objective of this effort was to evaluate, in detail, the properties,formability, and stability of non-toxic materials proposed to be used asprojectile cores. A laboratory study was conducted at ORNL to complimentthe larger manufacturing and testing effort described in this report.Issues such as density hardness, elastic behavior, and chemicalcompatibility were examined. The following presents a summary of theresults from this study.

Mechanical Properties

Samples of each material were tested in compression to determinestrength, modulus, and elastic behavior. A load was applied to the endsof the core samples at a rate of 0.02 in/min. Load versus displacementinformation was recorded along with information about the deformationand failure of the material. Hardness was then measured in Brinell Busing a drop hammer technique with a large diameter ball. Fourmeasurements were taken on the polished cross sections on three each ofthe material samples and the twelve values were then averaged.Calculated mechanical properties are shown below.

TABLE 29 Summary of Mechanical Properties of Non-Lead MaterialsCompressive Compressive Strength Modulus Hardness Sample Density (g/cc)(ksi) (Msi) (Brinell B) TRI #1 10.35 + 0.81 10.09 + 0.02 1.01 + 0.12165.7 + 50.2 TRI #2  8.80 + 1.13  9.74 + 0.41 0.79 + 0.08 145.8 + 39.1Pb-6% Sb* 10.9 4.1 4.0 90 (approx.) *Used a reference material

In addition to these tests, the effects of compressing the materials toa larger diameter at different pressures were studied. Three specimensof each material were pressed to a diameter of 0.224″ at pressures of50, 60, and 75 ksi. Each specimen was weighed and measured prior tocompression. Parts were inserted into a die and a load was applied toboth ends of the sample. The load was applied until the punch movementstopped and was then held for 5 seconds. When the load was removed thepart was immediately ejected, weighed and measured. Samples weremeasured again four weeks later to assess the time dependent elasticresponse of the materials. The diameters of the TRI#1 samples expanded0.02 to 0.04 in. while the TRI#2 sample diameters increasedapproximately 0.02 in. over the four week period.

TABLE 30 Recompression Densities Density Density Density (50 Ksi) (60Ksi) (75 Ksi) Sample (g/cc) (g/cc) (g/cc) TRI #1 10.36 + 0.36 10.55 +0.28 10.43 + 0.17 TRI #2  8.57 + 0.31  9.02 + 0.31  8.51 + 0.58

Chemical Compatibility

Core samples were also exposed to chemicals which would likely beencountered during manufacture, handling, and processing. These includedwater, acetone, isopropyl alcohol, and ethyl acetate. Individual coreswere weighed, measured, and visually examined prior to exposure. Sampleswere then placed in a 15 mL Nalgene bottle containing 10 mL of thesolvent. After 24 hours of submersion the samples were removed, dried,weighed and visually examined. Samples were then quickly resubmerged foran additional 4 days after which time the samples were again weighed andexamined. Overall, in terms of weight change and surface texture,solvents had little effect on the TRI#1 and TRI#2 samples. A summary ofthe chemical compatibility test results are provided below.

TABLE 31 Chemical Compatibility Results Initial Weight Weight WeightWeight (24 hrs.) (5 days) Change Sample (grams) (grams) (grams) (grams)Surface Change ACETONE: TRI#1 2.048 2.048 2.048 0.0 No change TRI#21.811 1.811 1.811 0.0 No change ETHYL ACETATE: TRI#1 2.013 2.014 2.0130.0 Slight discoloration TRI#2 1.775 1.775 1.776 +0.001 No changeISOPROPYL ALCOHOL: TRI#1 1.918 1.919 1.920 +0.002 Surface washed outTRI#2 1.849 1.849 1.849 0.0 No change WATER: TRI#1 2.016 2.015 2.016 0.0No change TRI#2 1.832 1.831 1.832 0.0 No change

Conclusions Recommendations

Projectile performance was evaluated based on existing requirements,where applicable, or on the basis of the best overall performer during aparticular test. Score factors were then assigned to each candidate foreach test. No score factors were given for the Kevlar® helmetpenetration test due to the variation in projectile velocities resultingfrom the reduced propellant charges, which affected terminalperformance. After testing was completed, the scores were totaled andare presented in the tables below. The first table provides a comparisonof the dimensional uniformity of the cores and assembled projectileswith respect to specification dimensional requirements. The second tableshows a comparison of the ballistic performance of each candidate. Ingeneral, the best performers in this ballistic performance category hadeither the smallest dispersion or achieved the most significant targeteffects in terms of soft target damage or hard target penetration.

Based on the tests conducted and the scoring methodology used, the TRI#1tungsten-Nylon 12® composite is an acceptable substitute for leadantimony. Any future efforts may expand on the testing already conductedand include rough handling, weapon compatibility, and barrel erosiontesting.

Criteria TRI#1 TRI#2 Control Core Dimensions 13.3 24.3 16.8 BulletInspection 5.06 10.73 5.72 Bullet Inspection (Fixed Gage) 1.33 1.56 0.07Total (Dimensions) 19.69 36.59 22.59

TABLE 32 Final Score and Ranking Criteria TRI#1 TRI#2 Control Dispersion11.08 11.12 13.71 Gelatin @ 10m 1.19 1.16 1.28 Gelatin @ 300m 1.11 1.211.00 Gelatin/PASGT Vest 1.13 1.17 1.09 Gelatin/Auto Glass 1.12 1.34 1.03Gelatin/Auto Glass (45) 1.00 1.46 1.05 R50 Al Plate 1.00 1.02 1.02 R50Steel Plate 1.25 1.43 1.30 Recovery 1.68 1.00 1.31 Total (Ballistics)20.56 20.91 22.79

EXAMPLE V Compounding Processes

Two compounding processes are applicable for the production of highdensity composite materials, namely batch processing and continuousprocessing. Batch processing utilizes a Brabender or Banbury type batchmixer and continuous processing utilizes a single or double screwcompounding-extruder machine. Each compounding process used to producetungsten powder/Nylon 12® composite material is described below.

Batch Compounding Process:

The first step of this process is to prepare a tungsten powder mixturecomprising a 2 to 40 micron particle size. Then, stainless steel fibersare prepared with a length of 0.125 inches and a diameter of 75 micronsand Nylon 12® fine powder material is prepared with a 0 to 80 micronparticle size.

A Brabender or Banbury batch mixer is heated to the melt temperature ofNylon 12®(480 degrees F.) and a measured quantity of Nylon 12® powder isintroduced into the batch mixer and allowed to melt. Meanwhile, thetungsten powder mixture and stainless steel fiber are heated to 480degrees F.

A measured quantity of tungsten powder mixture is gradually added to theNylon 12® material in the batch mixer until the required material mixratio is achieved. Then, a measured quantity of stainless steel fiber isgradually added to the tungsten powder/Nylon 12® mixture in the batchmixer until the required high density composite material mix ratio isachieved.

The molten high density composite material is fed into a screw extruder.The high density composite material is extruded as thin diameter rodfrom the extruder into a quenching water bath. The cooled solidifiedhigh density composite material extruded rod is fed from the quenchingbath into a pelletizer, which cuts the extruded high density compositematerial rod into pellets. The pellets are then suitable for injectionmolding or other methods for molding the composition into a variety ofshapes.

Continuous Compounding Process:

The tungsten powder, stainless steel fiber, and Nylon 12® powder areprepared according to the specifications described for the batchcompounding process above.

A single or double screw continuous compounding-extruder machine isheated to the melt temperature of Nylon 12®(480 degrees F.). Thetungsten powder mixture and stainless steel fiber are heated to 480degrees F.

A metered quantity of Nylon 12® powder and tungsten powder mixture isintroduced into the front end of the continuous compounder-extruder. Ametered quantity of tungsten powder mixture and stainless steel fiber isadded into the continuous compounder-extruder at one or more fill portslocated down stream on the compounder until the required high densitycomposite material mix ratio is achieved.

The high density composite material is extruded as thin diameter rodfrom the compounder-extruder into a quenching water bath. The cooledsolidified high density composite material extruded rod is fed from thequenching bath into a pelletizer which cuts the extruded high densitycomposite material rod into pellets.

EXAMPLE VI Tungsten Composites for use in Recreational Applications

Fishing Hardware

Lead sinkers of all types are currently used in a variety of fishinghardware. This application of the present invention is ideal from acommercialization standpoint, since lead poses a toxic danger towildlife, as well as lakes, rivers and streams. Most sinkers are fromabout {fraction (1/32)} to about ½ oz., and have been traditionally madeof lead. Alternative compositions for sinkers include brass, steel, andiron powder/polymer composites. Such compounds have, however, thedisadvantage of having less density, and thus give a bulkier profile tothe lure, which may offer negative clues to the fish. Fishingapplications include, for example, jigheads, worm weights, crankbaitweights, split shot, weighted hooks, jigging spoons, bait walkers andbottom bouncers. The present inventors have constructed jigheads andworm weights utilizing a tungsten powder/Nylon 12® composite. Theseweights, which have a density of about 11.0 g/cc, are shown in FIG. 24.

Hobby Applications

Hobby Applications represent a further use for the instant compositions.For example, model trains engines depend on having the maximum possibleengine weight to prevent wheel slippage. These engines are manufacturedto scale and space inside these small models is limited, so that highdensity is important in obtaining the desired overall weight in scalewith the model proportions. Engine frames molded from this material areone application. Also, “add-on” weights made of the present materialwould be utilized not only in model train engines, but in train cars aswell. FIG. 25 shows a commercially available lead model train add-onweight with a lead-free weight that is made of tungsten powder/nylon andhas a density of about 11.0 g/cc.

EXAMPLE VII Alternative Tungsten Composites Applications

Radiation Shielding

Tungsten is an excellent radiation shield material, but is difficult towork with in solid form. The injection moldable lead replacementaccording to the present invention solves this problem, since thematerial may be used to form radiation shield parts for all members ofthe medical x-ray and gamma ray equipment industry. This high densitymaterial has the advantage of superior structural strength when comparedto lead. Also, the material may be used to manufacture clothing used byradiation industry workers for protection against the effects ofionizing radiation.

Testing of Sheet Material of Polymeric Material

Sheet material of tungsten composite materials were placed on a piece ofx-ray film with 6 pieces of lead of varying thickness up to 0.25 inches.The samples of the present invention were compared to lead of 0.125inches thick. The samples were irradiated, and the film was developedand assessed for the ability of the samples to prevent film fogging.

In one example, material 0.250 inches thick and comprising the Nylon12®/polymer mix as set forth above, had a shielding equivalency ofapproximately that of 0.150 inches of sheet lead. In another example,material 0.50 inches thick, and comprising the Nylon 12® sample withstainless steel fibers as set forth above, yielded an approximateshielding equivalency of 0.187 inches of sheet lead. A third example was0.375 inches thick and flexible in form, had a shielding equivalency ofbetween about 0.94 and 0.125 inches of lead.

In other tests, samples of the composites of the present invention weretested for their mechanical properties as radiation shield components.Sample A1 was a tungsten/Nylon 12® non irradiated composite; sample A2was a tungsten/Nylon 12® composite irradiated with 38400 Roentgens;sample B1 was a tungsten/Nylon 12®/stainless steel fiber, non-irradiatedcomposite and sample B2 was a tungsten/Nylon 12®/stainless steel fibercomposite irradiated with 38400 Roentgens.

Samples A1, B1, A2 and B2 were conditioned at 25° C. and 50% RH for aperiod of 48 hours in an environmental chamber prior to testing. Thesamples were then tested in a universal testing machine using acrosshead control method. The results are presented in Table 33.

A1 B1 A2 B2 File Number L6-67322 L6-67324 L6-67323 L6-67325 TensileStrength (psi) 6,306 7,257 7,088 7,698 Yield Strength (psi) 5,517 *6,694 * Elongation-0.5 in. (%) ˜1.0 ˜0.5 ˜1.0 ˜0.5 * Sample broke beforethe yield point was reached.

Putty

In another example, a polyurethane resin putty and tungsten powder aremixed with an activator, which cures to form a flexible material. Arepresentative formulation for the putty comprises 2100 grams oftungsten powder (specific gravity=19.35) mixture blended into 300 gramsof TECHTHANE 425 polyurethane prepolymer (specific gravity=1.11). Thefinal mixture has a specific gravity of about 6.3. For use, 100 grams ofputty is mixed with 10 grams of ETHACURE 300 curative and allowed tocure at room temperature.

Other thermosetting materials include those listed in Table 34 and Table35 below. Table 34 lists possible thermoplastic materials that can befilled with the tungsten powder compositions of the present invention.Table 35 shows examples of thermoset materials for use in the presentinvention.

TABLE 34 Thermoplastic Materials that can be used in the composites ofthe present invention Acrylics Polymethyl Methacrylate Homopolymer andCoppolymer Polyoxymethylenes Acetals Acrylonitrile-Butadiene-StyreneMonsanto, Dow Chemical, Borg Warnar Chemicals Cycolac tradename MajorSupplier Thermoplastic Fluoropolymers Coflon (polyvinylidene fluoride)Ionomers Surlyn tradename for DuPont Product Polyamides NylonsPolyamide-imides Condensation product of aromatic diamines andtrimellitic anhydride Polyacrylates PolyhydroxyethylmethacrylatePolyetherketones Amoco Performance Products Polyaryl Sulfones AmocoPerformance Products Polybenzimidazoles Hoechst Celanese PolycarbonatesLexan manufactured by G.E. Polybutylene Terephthalates Valoxmanufactured by G.E. Polyether imides General Electric Company PolyetherSulfones ICI Advanced Materials Thermoplastic Polyimides Ciba GeigyCorporation Thermoplastic Polyurethanes Estane Line B.F.Goodrich, TexinLine Bayer Polyphenylene Sulfides Ryton, Phillips Petroleum PolyethyleneUltrahigh Molecular Weight and Low Molecular Weight, Hoechst CelanesePolypropylene Phillips Petroleum Polysulfones Amoco Performance ProductsPolyvinyl Chlorides B.F. Goodrich Styrene Acrylonitriles Dow ChemicalPolystyrenes Mobil Polyphenylene Ether Blends Borg Warner ChemicalsStyrene Maleic anhydrides Arco Chemical Company Polycarbonates GeneralElectric Company

TABLE 35 Thermosets Materials that can be used in the composites of thepresent invention Allyls Osaka Soda Company Aminos American CyanamidCyanates Dow Chemical Epoxies Bisphenol A type epoxies and acrylkatemodified epoxies with aliphatic and aromatic amine curing agents, CibaGeigy and Shell Phenolics Resole and Novalacs Occidental ChemicalUnsaturated Polyesters Ashland Chemical Bismaleimides Ciba GeigyPolyurethanes Polyether and Polyester polyurethanes Silicones DowCorning Corporation Vinyl Esters Ashland Chemical Corporation UrethaneHybrids Urethane Acrylates and urethane epoxies

A specific example of using Tungsten powder with a thermosetting Epoxyis as follows. 27.7 grams of Tungsten powder was weighed in a beaker andset aside. Subsequently 5.0 grams of Epon 8111 of an acrylate modifiedepoxy was weighed into another container to which was immediately added0.5 grams of Shell Epi-Cure 3271. Then 3.6 grams of the mixed epoxy andcuring agent was added to the 27.7 grams of Teledyne C-8 Tungstenpowder. The powder and the epoxy were hand mixed, placed between twoTeflon sheets and allowed to cure overnight. A flexible sample ofTungsten powder epoxy was produced.

Foam

A polyurethane rigid foam can also be produced using the compositions ofthe present invention. The foam was produced by adding 238 grams ofTeledyne C8 Tungsten powder to 109.9 grams of Premium Polymer 475-20 Bcomponent and the mixture was stirred. Next 12® grams of Premium Polymer475-20 A component was added and the slurry stirred for approximatelytwenty seconds. The slurry was placed in a container. It quickly roseand was tack free within two minutes. The tungsten powder was uniformlydistributed throughout the foam. It is envisioned that the foam materialmay be employed in a binder capacity as defined elsewhere herein. Thehigh density foam will find utility in noise and vibration damping, inradiation shielding and the like.

Slurry

In certain other embodiments, the compositions of the present inventionmay be employed to produce a high density, low viscosity slurry. Such aslurry may be employed in list systems of deep submerge rescue vesselsor remote operated vehicles, in a manner similar to the current uses ofmercury therein.

In present systems mercury is transferred between spherical chambers tocause list to port or starboard or to change the distance between thecenter of buoyancy and the center of gravity. The list system of suchvessels involves the transfer of approximately 2800 pounds of mercurybetween a reservoir which is low and centered athwart ships and the portand starboard wing tanks which are located 45° above the horizontal andas far outboard as possible. All the tanks are spherical and equippedwith a diaphragm, which is actuated by hydraulic fluid to displace themercury. The spherical tanks are located between and in close proximityto the center and aft personnel spheres, the skin and the structuralrings that serve as the aft support for the personnel pressure capsule.The tanks are connected by 1.25 inch outside diameter stainless steeltubing and the mercury can be transferred between the reservoir and awing tank in 45 seconds representing a flow of about 25 gpm.

When such systems were designed, mercury was thought to be the idealfluid for such weight modulation, however, the toxic nature of mercurymakes it an extremely hazardous material for this purpose. Hence analternative is needed. U.S. Pat. No. 5,349,915 (incorporated herein byreference) describes tungsten balls in a tube of hydraulic fluid as aweight medium for deep submersibles.

The compositions of the present invention provide a high densitycomposite material that may be used as a weight medium for trim and listsystems. Such compositions may be configured into a high density slurrycomprising solvents, suspension agents, surfactants and lubricants. Thehigh density material of the present invention may be in the form ofhigh density balls or in the form of a powder mixture in the slurry.

The solvent of choice may be a perfluorpolyether, other examples includecastor oils, tricresyl phosphate, polyoxypropylene ether glycols,polymethylphenyl siloxane, fluorosilicone, paratherm NF, therminol,dynalene, tribolube F-219, perfluorinated hydrocarbons, fomalin 1818perfluorpolyether, Voranol 5070 perfluorpolyether, Voranolperfluorpolyether 5004, and Veranol perfluorpolyether 2004. These fluidsexhibit good viscosity, compatibility, and volatility and arecompatible-with stainless steel, tungsten, Teflon, synthetic rubber andViton.

The surfactant of choice may be anionic, cationic or nonanionic innature. Silicon and fluorosilicone surfactants may also be employed. Thetungsten composites of the present invention may be in powder form or inthe form a balls. Polymeric encapsulation may be employed with thetungsten powder or balls to reduce friction in the slurry.Urea-formaldehyde emulsions, glyco diols and melamine formaldehydecompositions are good candidates as encapsulations materials.

In an exemplary slurry 700 g tungsten powder (2-4 micron) are mixed with100 g 60 wt. motor oil (specific gravity 1.1) and 800 g ballast material1 (specific gravity 6.3). In another embodiment, 350 g tungsten powder(8-10 microns) are blend with 50 g 80-140 wt. gear case oil (specificgravity 1.1), and 400 g of ballast material 2 ® specific gravity 6.3).

All of the compositions and methods disclosed and claimed herein can bemade and executed without undue experimentation in light of the presentdisclosure. While the compositions and methods of this invention havebeen described in terms of preferred embodiments, it will be apparent tothose of skill in the art that variations may be applied to thecomposition, methods and in the steps or in the sequence of steps of themethod described herein without departing from the concept, spirit andscope of the invention. More specifically, it will be apparent thatcertain agents which are both chemically and physiologically related maybe substituted for the agents described herein while the same or similarresults would be achieved. All such similar substitutes andmodifications apparent to those skilled in the art are deemed to bewithin the spirit, scope and concept of the invention.

REFERENCES

The following references, to the extent that they provide exemplaryprocedural or other details supplementary to those set forth herein, arespecifically incorporated herein by reference.

U.S. Pat. No. 5, 189,252

PCT Application No. WO 92/08346

U.S. Pat. No. 5,081,786

U.S. Pat. No. 3,546,769

U.S. Pat. No. 4,428,295

U.S. Pat. No. 5,399,187

Shooting Sportsman, July/August 1995, pp. 9-12

U.K. Patent Application No. GB 2179664A

What is claimed is:
 1. A method for manufacturing a high densitycomposite, comprising the steps of: providing a polymeric binder;providing tungsten powder, wherein the tungsten powder further comprisesa first group of particles having sizes of between about 2 microns andabout 8 microns; and a second group of particles having sizes of betweenabout 20 microns and 40 microns; mixing the tungsten powder with thepolymeric binder at approximately the melting point of the polymericbinder into a tungsten powder/polymeric binder mixture; and pelletizingthe tungsten powder/polymeric binder mixture into a composition.
 2. Amethod for manufacturing a high density composite, comprising the stepsof: providing a binder; providing tungsten powder, wherein the tungstenpowder comprises a first group of particles having sizes in a firstrange, a second group of particles having sizes in a second range, and athird group of particles having sizes in a third range; mixing thetungsten powder with the binder at approximately the melting point ofthe binder into a tungsten powder/binder mixture; and pelletizing thetungsten powder/binder mixture into a composition.
 3. The method ofclaim 1 further including the steps of: molding the tungstenpowder/polymeric binder mixture into a composition having a specificgravity of at least 11.0.
 4. The method of claim 3 wherein the step ofmolding comprises injection molding.
 5. The method of claim 1, whereinthe first group of particles further comprises: a third group ofparticles having sizes of between about 2 microns and about 4 microns;and a fourth group of particles having sizes of between about 4 micronsand about 8 microns.
 6. The method according to claim 3, wherein thepolymeric binder comprises at least one of cellulose, fluoro-polymer,ethylene inter-polymer alloy elastomer, ethylene vinyl acetate, ionomer,nylon, polyether imide, polyamide, polyurethane, polyester elastomer,polyester sulfone, polyphenyl amide, polypropylene, polyvinylidenefluoride or thermoset polyurea elastomer, acrylics, homopolymers,acetates, copolymers, acrylonitrile-butadinen-styrene, thermoplasticfluoro polymers, inomers, polyamides, polyamide-imides, polyacrylates,polyatherketones, polyaryl-sulfones, polybenzimidazoles, polycarbonates,polybutylene, terephthalates, polyether imides, polyether sulfones,thermoplastic polyimides, thermoplastic polyurethanes, polyphenylenesulfides, polyethylene, polypropylene, polysulfones, polyvinylchlorides,styrene acrylonitriles, polystyrenes, polyphenylene, ether blends,styrene maleic anhydrides, polycarbonates, allyls, aminos, cyanates,epoxies, phenolics, unsaturated polyesters, bismaleimides,polyurethanes, silicones, vinylesters, or urethane hybrids.
 7. Themethod of claim 1, wherein the step of providing a polymeric binderfurther comprises the steps of: freezing the polymeric binder; andgrinding the frozen polymeric binder into particles.
 8. The method ofclaim 3, wherein the step of molding further comprises the steps of:molding the tungsten powder/polymeric binder mixture into a projectilehaving a specific gravity of at least 11.0.
 9. The method of claim 8,wherein the step of molding further comprises the steps of: molding thetungsten powder/polymeric binder mixture into shot having a specificgravity of at least 11.0.